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display: inline-block;">6</div>SQL映射文件之自定义映射元素</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-95d837d1 data-v-95d837d1><div class="item" data-v-95d837d1><div class="indicator" data-v-95d837d1></div><a class="VPLink link link" href="/courses/mybatis/01-MyBatis%E5%9F%BA%E7%A1%80/07-SQL%E6%98%A0%E5%B0%84%E6%96%87%E4%BB%B6%E4%B9%8B%E7%BC%93%E5%AD%98%E5%85%83%E7%B4%A0" data-v-95d837d1><!--[--><p class="text" data-v-95d837d1><div class="text-color-gray mr-[6px]" style="font-weight: 550; display: inline-block;">7</div>SQL映射文件之缓存元素</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-95d837d1 data-v-95d837d1><div class="item" data-v-95d837d1><div class="indicator" data-v-95d837d1></div><a class="VPLink link link" href="/courses/mybatis/01-MyBatis%E5%9F%BA%E7%A1%80/08-%E5%8A%A8%E6%80%81SQL" data-v-95d837d1><!--[--><p class="text" data-v-95d837d1><div class="text-color-gray mr-[6px]" style="font-weight: 550; display: inline-block;">8</div>动态SQL</p><!--]--></a><!----></div><!----></div><!--]--></div></section></div><div class="group" data-v-802ad7d8><section class="VPSidebarItem level-0 collapsible has-active" data-v-802ad7d8 data-v-95d837d1><div class="item" role="button" tabindex="0" data-v-95d837d1><div class="indicator" data-v-95d837d1></div><h2 class="text" data-v-95d837d1>MyBatis-Plus基础 (5篇)</h2><div class="caret" role="button" aria-label="toggle section" tabindex="0" data-v-95d837d1><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" viewbox="0 0 24 24" class="caret-icon" data-v-95d837d1><path d="M9,19c-0.3,0-0.5-0.1-0.7-0.3c-0.4-0.4-0.4-1,0-1.4l5.3-5.3L8.3,6.7c-0.4-0.4-0.4-1,0-1.4s1-0.4,1.4,0l6,6c0.4,0.4,0.4,1,0,1.4l-6,6C9.5,18.9,9.3,19,9,19z"></path></svg></div></div><div class="items" data-v-95d837d1><!--[--><div class="VPSidebarItem level-1 is-link" data-v-95d837d1 data-v-95d837d1><div class="item" data-v-95d837d1><div class="indicator" data-v-95d837d1></div><a class="VPLink link link" href="/courses/mybatis/02-MyBatis-Plus%E5%9F%BA%E7%A1%80/01-%E5%BF%AB%E9%80%9F%E5%85%A5%E9%97%A8" data-v-95d837d1><!--[--><p class="text" data-v-95d837d1><div class="text-color-red mr-[6px]" style="font-weight: 550; display: inline-block;">1</div>快速入门</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-95d837d1 data-v-95d837d1><div class="item" data-v-95d837d1><div class="indicator" data-v-95d837d1></div><a class="VPLink link link" href="/courses/mybatis/02-MyBatis-Plus%E5%9F%BA%E7%A1%80/02-%E5%A2%9E%E5%88%A0%E6%94%B9%E6%93%8D%E4%BD%9C" data-v-95d837d1><!--[--><p class="text" data-v-95d837d1><div class="text-color-orange mr-[6px]" style="font-weight: 550; display: inline-block;">2</div>增删改操作</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-95d837d1 data-v-95d837d1><div class="item" data-v-95d837d1><div class="indicator" data-v-95d837d1></div><a class="VPLink link link" href="/courses/mybatis/02-MyBatis-Plus%E5%9F%BA%E7%A1%80/03-%E7%AE%80%E5%8D%95%E6%9F%A5%E8%AF%A2%E6%93%8D%E4%BD%9C" data-v-95d837d1><!--[--><p class="text" data-v-95d837d1><div class="text-color-yellow mr-[6px]" style="font-weight: 550; display: inline-block;">3</div>简单查询操作</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-95d837d1 data-v-95d837d1><div class="item" data-v-95d837d1><div class="indicator" data-v-95d837d1></div><a class="VPLink link link" href="/courses/mybatis/02-MyBatis-Plus%E5%9F%BA%E7%A1%80/04-%E6%9D%A1%E4%BB%B6%E6%9E%84%E9%80%A0%E5%99%A8" data-v-95d837d1><!--[--><p class="text" data-v-95d837d1><div class="text-color-gray mr-[6px]" style="font-weight: 550; display: inline-block;">4</div>条件构造器</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-95d837d1 data-v-95d837d1><div class="item" data-v-95d837d1><div class="indicator" data-v-95d837d1></div><a class="VPLink link link" href="/courses/mybatis/02-MyBatis-Plus%E5%9F%BA%E7%A1%80/05-%E4%BB%A3%E7%A0%81%E7%94%9F%E6%88%90%E5%99%A8" data-v-95d837d1><!--[--><p class="text" data-v-95d837d1><div class="text-color-gray mr-[6px]" style="font-weight: 550; display: inline-block;">5</div>代码生成器</p><!--]--></a><!----></div><!----></div><!--]--></div></section></div><!--]--><!--[--><!--]--></nav></aside><div class="VPContent has-sidebar" id="VPContent" data-v-03322d68 data-v-2c336b25><div class="VPDoc has-sidebar has-aside" data-v-2c336b25 data-v-53ed897c><!--[--><!--]--><div class="container" data-v-53ed897c><div class="aside" data-v-53ed897c><div class="aside-curtain" data-v-53ed897c></div><div class="aside-container" data-v-53ed897c><div class="aside-content" data-v-53ed897c><div class="VPDocAside" data-v-53ed897c data-v-3d450548><!--[--><!--]--><!--[--><!--]--><div class="VPDocAsideOutline" role="navigation" data-v-3d450548 data-v-70b38f01><div class="content" data-v-70b38f01><div class="outline-marker" data-v-70b38f01></div><div class="outline-title" role="heading" aria-level="2" data-v-70b38f01>目录</div><nav aria-labelledby="doc-outline-aria-label" data-v-70b38f01><span class="visually-hidden" id="doc-outline-aria-label" data-v-70b38f01> Table of Contents for current page </span><ul class="root" data-v-70b38f01 data-v-e10534d6><!--[--><!--]--></ul></nav></div></div><!--[--><!--]--><div class="spacer" data-v-3d450548></div><!--[--><!--]--><!----><!--[--><!--]--><!--[--><!--]--></div></div></div></div><div class="content" data-v-53ed897c><div class="content-container" data-v-53ed897c><!--[--><!--]--><!----><main class="main" data-v-53ed897c><div style="position:relative;" class="vp-doc _courses_mybatis_02-MyBatis-Plus%E5%9F%BA%E7%A1%80_04-%E6%9D%A1%E4%BB%B6%E6%9E%84%E9%80%A0%E5%99%A8" data-v-53ed897c><div><h1 id="条件构造器" tabindex="-1">条件构造器 <a class="header-anchor" href="#条件构造器" aria-label="Permalink to "条件构造器""></a></h1><!----><h2 id="前言" tabindex="-1">前言 <a class="header-anchor" href="#前言" aria-label="Permalink to "前言""></a></h2><p><strong>C：</strong> 在前两篇 MP 的 CRUD API 演示中，笔者一直刻意忽略了一些带有条件构造器的 API，你说哪些是带有条件构造器的 API ？看下面。</p><ul><li><code>update(T entity, Wrapper<T> updateWrapper) : int</code></li><li><code>delete(Wrapper<T> queryWrapper) : int</code></li><li><code>selectOne(Wrapper<T> queryWrapper) : T</code></li><li><code>selectCount(Wrapper<T> queryWrapper) : Integer</code></li><li><code>selectList(Wrapper<T> queryWrapper) : List<T></code></li><li><code>selectMaps(Wrapper<T> queryWrapper) : List<Map<String, Object>></code></li><li><code>selectObjs(Wrapper<T> queryWrapper) : List<Object></code></li><li><code>selectPage(E page, Wrapper<T> queryWrapper) : E</code></li><li><code>selectMapsPage(E page, Wrapper<T> queryWrapper) : E</code></li></ul><p>看到了吧？上述这些 API 中，都有一个显著的特点，即要求传递一个 Wrapper 类型的参数，而这个 Wrapper 类型就是笔者提到的条件构造器。</p><p>预热了两篇之久，本篇，笔者将带着你入门 MP 的条件构造器，看看传统的 SQL 语句条件如何用 条件构造器API 组装出来。</p><p><img src="/assets/202101241302860.fkxfRFWp.jpg" alt="202101241302860"></p><h2 id="概述" tabindex="-1">概述 <a class="header-anchor" href="#概述" aria-label="Permalink to "概述""></a></h2><p>Wrapper 类型，顾名思义就是一个包装类，但它又不是我们常说的 Integer 这种包装类概念，在 MP 中它是用于包装各种丰富的查询条件的包装类。</p><p>它是 MP 中条件包装类的顶级类，笔者在下方给你列出了它的类层次结构。当然，枝繁叶茂的它不可能就这几个子类，笔者只不过是挑重点的展示一下而已。</p><p><img src="/assets/202101241303960.vdvVMZhn.png" alt="202101241303960."></p><p>但Wrapper 类是一个抽象类，所以我们不可能直接使用它，而是需要使用它的子类，那么哪些子类是我们常用的呢？一共有4个。</p><ul><li><p><code>QueryWrapper</code>：查询条件构造器</p></li><li><p><code>UpdateWrapper</code>：更新条件构造器</p></li><li><p><code>LambdaQueryWrapper</code>：使用 Lambda 语法的查询条件构造器</p></li><li><p><code>LambdaUpdateWrapper</code>：使用 Lambda 语法的更新条件构造器</p></li></ul><p>接下来笔者就以 <code>QueryWrapper</code> 和 <code>LambdaQueryWrapper</code> 为例，带着大家体验一下条件构造器。至于其他两个，使用方法没有太大差别，所以笔者不再单独讲解了。</p><p>我们还是先CV一个专用于条件构造器的单元测试类。</p><p><img src="/assets/202101241303970.gZ8wRV92.gif" alt="202101241303970"></p><h2 id="querywrapper" tabindex="-1">QueryWrapper <a class="header-anchor" href="#querywrapper" aria-label="Permalink to "QueryWrapper""></a></h2><p>QueryWrapper 是 MP 中主要用于查询操作的条件包装类，我们将借助《快速入门》篇提到过的查询实体列表 API 来测试一下它。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 其他 API 略</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> interface</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> BaseMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">T</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">> </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">extends</span><span style="--shiki-light:#6F42C1;--shiki-dark:#6CB6FF;"> Mapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">T</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">> {</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> /**</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 根据 entity 条件，查询全部记录</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> *</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@param</span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;"> queryWrapper</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 实体对象封装操作类（可以为 null）</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List<</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">T</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">> </span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Param</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Constants.WRAPPER) Wrapper<</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">T</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">> </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">queryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p>下方的基础 SQL 查询语法，大家应该都不陌生吧？</p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> [ALL | DISTINCT] </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 是否去重</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">*</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> | table_name.</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">*</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> | [table_name.field1 [AS alias1] [, table_name.field2 [AS alias2]][, ...]]} </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 查询哪些列</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> table_name [AS table_ alias] [, ...] </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 从哪些表查询</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> [LEFT | RIGHT | INNER JOIN table_name2 [AS table_alias] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">ON</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> 关联条件] </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 连接查询</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[WHERE ...] </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 根据条件来完成上述表数据的筛选</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[GROUP BY …] </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 根据一个或多个列分组</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[HAVING …] </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 分组查询后的筛选条件</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[ORDER BY… ] </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 根据一个或多个列排序</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[LIMIT {[offset,] row_count}] </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">-- 限制查询结果数量和范围</span></span></code></pre></div><p>笔者就是要以 QueryWrapper ，带大家体验一下如何用条件构造器，来实现上述的基础 SQL 查询。</p><h3 id="指定查询的列" tabindex="-1">指定查询的列 <a class="header-anchor" href="#指定查询的列" aria-label="Permalink to "指定查询的列""></a></h3><p>在写查询类 SQL 时，我们都要先指定好要查询哪些列。在 MP 的查询条件构造器中，可以通过 <code>select()</code> 方法来实现查询列的指定。</p><ul><li><code>select(String... columns) : QueryWrapper<T></code></li><li>...</li></ul><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询用户的姓名和年龄信息</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 指定查询 name、age 两列数据</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">select</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"name"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Preparing</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> SELECT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> name</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">,age </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"> user </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Columns</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> name, age</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Row</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Jone, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Row</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Jack, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">20</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Row</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Tom, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">28</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Row</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Sandy, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Row</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Billie, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Total</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 5</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=null, name=Jone, age=18, email=null, createTime=null, updateTime=null, isDelete=null)</span></span>
|
||
<span class="line"><span>User(id=null, name=Jack, age=20, email=null, createTime=null, updateTime=null, isDelete=null)</span></span>
|
||
<span class="line"><span>User(id=null, name=Tom, age=28, email=null, createTime=null, updateTime=null, isDelete=null)</span></span>
|
||
<span class="line"><span>User(id=null, name=Sandy, age=21, email=null, createTime=null, updateTime=null, isDelete=null)</span></span>
|
||
<span class="line"><span>User(id=null, name=Billie, age=24, email=null, createTime=null, updateTime=null, isDelete=null)</span></span></code></pre></div><p>而且，你还可以借助这个方法实现结果去重功能，只需要在第一个指定的列名前添加 <code>DISTINCT</code> 关键字即可。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 指定查询 name、age 两列数据,并去重结果</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">select</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"DISTINCT name"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span></code></pre></div><p>最终执行的 SQL 就变成了这样：</p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT DISTINCT</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,age </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span></code></pre></div><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>聪明如你，一定能举一反三，如果未来需要给查询列起别名、或者使用一些聚合函数，直接在 select() 方法中写就可以。</p></div><h3 id="where条件子句" tabindex="-1">where条件子句 <a class="header-anchor" href="#where条件子句" aria-label="Permalink to "where条件子句""></a></h3><p>查询类 SQL 中，在指定了查询哪些列之后，另一个非常重要的就是指定筛选结果数据的条件。</p><p>where 条件子句就是 <strong>用于检索数据表中符合条件记录</strong> 的，<strong>条件子句可以由一个或多个逻辑表达式组成，结果一般为真或假。</strong></p><h4 id="关系运算符" tabindex="-1">关系运算符 <a class="header-anchor" href="#关系运算符" aria-label="Permalink to "关系运算符""></a></h4><p>下方是 where 条件子句中常用关系运算 和 MP 中对应方法的对照表。</p><table><thead><tr><th><strong>SQL 运算符</strong></th><th style="text-align:left;"><strong>含义</strong></th><th><strong>MP 对应方法</strong></th><th>笔者帮你强化理解</th></tr></thead><tbody><tr><td>=</td><td style="text-align:left;">等于</td><td>eq(R column, Object val) : Children</td><td>eq：equal</td></tr><tr><td><> 或 !=</td><td style="text-align:left;">不等于</td><td>ne(R column, Object val) : Children</td><td>ne：not equal</td></tr><tr><td>></td><td style="text-align:left;">大于</td><td>gt(R column, Object val) : Children</td><td>gt：greater than</td></tr><tr><td><</td><td style="text-align:left;">小于</td><td>lt(R column, Object val) : Children</td><td>lt：less than</td></tr><tr><td>>=</td><td style="text-align:left;">大于等于</td><td>ge(R column, Object val) : Children</td><td>ge：greater than or equal</td></tr><tr><td><=</td><td style="text-align:left;">小于等于</td><td>le(R column, Object val) : Children</td><td>le：less than or equal</td></tr><tr><td>is null</td><td style="text-align:left;">等于null</td><td>isNull(R column) : Children</td><td></td></tr><tr><td>is not null</td><td style="text-align:left;">不等于null</td><td>isNotNull(R column) : Children</td><td></td></tr></tbody></table><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询年龄 >= 21 的用户数据</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // ge：greater equals 大于等于</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">ge</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Preparing: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id,</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,age,email,create_time,update_time,is_delete </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AND</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (age </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">>=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ?)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Columns: id, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email, create_time, update_time, is_delete</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">28</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Sandy, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Sandy@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Billie, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Billie@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Total: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=3, name=Tom, age=28, email=Tom@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
|
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<span class="line"><span>User(id=4, name=Sandy, age=21, email=Sandy@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
|
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<span class="line"><span>User(id=5, name=Billie, age=24, email=Billie@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span></code></pre></div><p>其他的笔者就不再测试了，你可以自己挨个试试。</p><h4 id="逻辑运算符" tabindex="-1">逻辑运算符 <a class="header-anchor" href="#逻辑运算符" aria-label="Permalink to "逻辑运算符""></a></h4><h5 id="普通逻辑" tabindex="-1">普通逻辑 <a class="header-anchor" href="#普通逻辑" aria-label="Permalink to "普通逻辑""></a></h5><table><thead><tr><th><strong>SQL 运算符</strong></th><th style="text-align:left;"><strong>含义</strong></th><th><strong>MP 对应方法</strong></th></tr></thead><tbody><tr><td><strong>AND</strong></td><td style="text-align:left;">逻辑与，同时为真，结果才为真</td><td>默认使用 and 作为多个条件之间的关系表示</td></tr><tr><td></td><td style="text-align:left;">嵌套 and</td><td>and(Consumer<Param> consumer) : Children</td></tr><tr><td><strong>OR</strong></td><td style="text-align:left;">逻辑或，只要一个为真，则结果为真</td><td>or() : Children</td></tr><tr><td></td><td style="text-align:left;">嵌套 or</td><td>or(Consumer<Param> consumer) : Children</td></tr><tr><td><strong>NOT</strong></td><td style="text-align:left;">逻辑非，若操作数为假，结果则为真</td><td>not(Consumer<Param> consumer) : Children</td></tr></tbody></table><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询年龄 >= 21 并且姓名为Tom的用户数据</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
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||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 可以分开设置</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // queryWrapper.ge("age", 21);</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // queryWrapper.eq("name", "Tom");</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 也可以链式操作</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">ge</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">)</span></span>
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||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> .</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">eq</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"name"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"Tom"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
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<span class="line"></span>
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||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
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||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Preparing: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id,</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,age,email,create_time,update_time,is_delete </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AND</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (age </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">>=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ? </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">AND</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> name</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ?)</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">), Tom(String)</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Columns: id, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email, create_time, update_time, is_delete</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">28</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Total: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=3, name=Tom, age=28, email=Tom@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span></code></pre></div><p>当你编写了多个条件表达式的时候，MP 默认认为它们之间采用 <code>and</code> 关系。但如果你想实现 <code>or</code> 关系的需求，那就必须得使用 <code>or()</code> 方法了。</p><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询年龄 = 18 或者 年龄 = 24 的用户数据</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 或者关系</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">eq</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> .</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">or</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">()</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> .</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">eq</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Preparing: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id,</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,age,email,create_time,update_time,is_delete </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AND</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (age </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ? </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">OR</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> age </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ?)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">), </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Columns: id, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email, create_time, update_time, is_delete</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Jone, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Jone@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Billie, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Billie@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Total: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=1, name=Jone, age=18, email=Jone@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
|
||
<span class="line"><span>User(id=5, name=Billie, age=24, email=Billie@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span></code></pre></div><h5 id="嵌套逻辑" tabindex="-1">嵌套逻辑 <a class="header-anchor" href="#嵌套逻辑" aria-label="Permalink to "嵌套逻辑""></a></h5><p>我们看到上方的对照表中，还有一种是用于嵌套 or 或 嵌套 and 关系的方法，有些同学可能有点懵，看看下面这行代码是不是就明白了呢？</p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">select</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> xx </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> xx </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">where</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> xx </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> xx </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">or</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (xx </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> xx </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">and</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> xx </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> xx)</span></span></code></pre></div><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询姓名中带有o字母 或者 (年龄 = 21 并且 姓名以S字母开头) 的用户数据</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList7</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">like</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"name"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"o"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> .</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">or</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> i.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">eq</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">).</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">likeRight</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"name"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"S"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">));</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Preparing: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id,</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,age,email,create_time,update_time,is_delete </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AND</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> LIKE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ? </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">OR</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (age </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ? </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">AND</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> name</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> LIKE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ?))</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters: %o%(String), </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">), S%(String)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Columns: id, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email, create_time, update_time, is_delete</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Jone, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Jone@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">28</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Sandy, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Sandy@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Total: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=1, name=Jone, age=18, email=Jone@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
|
||
<span class="line"><span>User(id=3, name=Tom, age=28, email=Tom@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
|
||
<span class="line"><span>User(id=4, name=Sandy, age=21, email=Sandy@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span></code></pre></div><h4 id="范围查询" tabindex="-1">范围查询 <a class="header-anchor" href="#范围查询" aria-label="Permalink to "范围查询""></a></h4><p>上面的 <code>or</code> 关系需求中，是对相同列的多个值的查询，这种情况在 SQL 中我们可以采用 in 查询来优化。而如果是对相同列的连续范围值的查询，则可以采用 between ... and ...查询来优化。</p><p>下方是 in 查询 和 between ... and ...查询与 MP 中方法的对照表。</p><table><thead><tr><th><strong>SQL 运算符</strong></th><th style="text-align:left;"><strong>含义</strong></th><th><strong>MP 对应方法</strong></th></tr></thead><tbody><tr><td>in (值1, 值2, ...)</td><td style="text-align:left;">在某个列表之间</td><td>in(R column, Object... values) : Children</td></tr><tr><td>not in (值1, 值2, ...)</td><td style="text-align:left;">不在某个列表之间</td><td>notIn(R column, Object... value) : Children</td></tr><tr><td>between ... and ...</td><td style="text-align:left;">在某个范围之间</td><td>between(R column, Object val1, Object val2) : Children</td></tr><tr><td>not between ... and ...</td><td style="text-align:left;">不在某个范围之间</td><td>notBetween(R column, Object val1, Object val2) : Children</td></tr></tbody></table><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
|
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<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询年龄 = 18 或者 年龄 = 24 的用户数据</span></span>
|
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
|
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 如果是对相同列的多个值查询，使用in查询优化</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
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||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
|
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Preparing: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id,</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,age,email,create_time,update_time,is_delete </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AND</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (age </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">IN</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (?,?))</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">), </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Columns: id, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email, create_time, update_time, is_delete</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Jone, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Jone@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Billie, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Billie@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Total: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=1, name=Jone, age=18, email=Jone@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
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<span class="line"><span>User(id=5, name=Billie, age=24, email=Billie@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span></code></pre></div><h4 id="模糊查询" tabindex="-1">模糊查询 <a class="header-anchor" href="#模糊查询" aria-label="Permalink to "模糊查询""></a></h4><p>除了精确的查询之外， 模糊查询也是使用频率很高的。下方是模糊查询 和 MP 中方法的对照表。</p><table><thead><tr><th><strong>SQL 运算符</strong></th><th style="text-align:left;"><strong>含义</strong></th><th><strong>MP 对应方法</strong></th></tr></thead><tbody><tr><td>like '%A%'</td><td style="text-align:left;">在某个范围之间</td><td>like(R column, Object val) : Children</td></tr><tr><td>not like '%A%'</td><td style="text-align:left;">不在某个范围之间</td><td>notLike(R column, Object val) : Children</td></tr><tr><td>like '%A'</td><td style="text-align:left;">查询</td><td>likeLeft(R column, Object val) : Children</td></tr><tr><td>like 'A%'</td><td style="text-align:left;">不在某个列表之间</td><td>likeRight(R column, Object val) : Children</td></tr></tbody></table><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询姓名中带有 o 字母的用户数据</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList6</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">like</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"name"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"o"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Preparing: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id,</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,age,email,create_time,update_time,is_delete </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AND</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> LIKE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ?)</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters: %o%(String)</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Columns: id, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email, create_time, update_time, is_delete</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Jone, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">18</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Jone@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">28</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Total: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=1, name=Jone, age=18, email=Jone@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
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<span class="line"><span>User(id=3, name=Tom, age=28, email=Tom@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span></code></pre></div><h3 id="分组查询" tabindex="-1">分组查询 <a class="header-anchor" href="#分组查询" aria-label="Permalink to "分组查询""></a></h3><p>好了，写了这么多个查询示例，笔者相信聪明的你已经悟了。我们本篇毕竟不是去讲解 SQL 语句的，所以笔者最后把分组查询和排序查询的 API 再列一下，你想测试就自行测试一下吧。</p><table><thead><tr><th><strong>SQL 运算符</strong></th><th style="text-align:left;"><strong>含义</strong></th><th><strong>MP 对应方法</strong></th><th>示例</th></tr></thead><tbody><tr><td>group by 列1, 列2</td><td style="text-align:left;">根据一个列或多个列分组</td><td>groupBy(R column) : Children</td><td>例: groupBy("id", "name")</td></tr><tr><td>having ...</td><td style="text-align:left;">分组查询后的筛选条件</td><td>having(String sqlHaving, Object... params) : Children</td><td>例1: having("sum(age) > 10") 例2：having("sum(age) > {0}", 10)</td></tr></tbody></table><h3 id="排序查询" tabindex="-1">排序查询 <a class="header-anchor" href="#排序查询" aria-label="Permalink to "排序查询""></a></h3><table><thead><tr><th><strong>SQL 运算符</strong></th><th style="text-align:left;"><strong>含义</strong></th><th><strong>MP 对应方法</strong></th><th>示例</th></tr></thead><tbody><tr><td>order by 列 ASC</td><td style="text-align:left;">按指定列升序排序</td><td>orderByAsc(R... columns) : Children</td><td>例: orderByAsc("id", "name")</td></tr><tr><td>order by 列 DESC</td><td style="text-align:left;">按指定列降序排序</td><td>orderByDesc(R... columns) : Children</td><td>例: orderByDesc("id", "name")</td></tr></tbody></table><h3 id="连接查询" tabindex="-1">连接查询 <a class="header-anchor" href="#连接查询" aria-label="Permalink to "连接查询""></a></h3><p>MP 的确很强大，但是它封装的接口都是针对单表的，所以如果我们要多表查询的时候，还是需要采用原生的 MyBatis 写法，这里笔者就不再介绍了。</p><h2 id="lambdaquerywrapper" tabindex="-1">LambdaQueryWrapper <a class="header-anchor" href="#lambdaquerywrapper" aria-label="Permalink to "LambdaQueryWrapper""></a></h2><p>LambdaQueryWrapper 和 QueryWrapper 只差一个 Lambda 语法的使用而已，不知道你是否还记得《快速入门》篇中介绍的 MP 特点，其中有一条就是：<strong>支持 Lambda 形式调用</strong> ：通过 Lambda 表达式，方便的编写各类查询条件，无需再担心字段写错。[1]</p><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询年龄 >= 21 的用户数据</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList8</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> LambdaQueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> LambdaQueryWrapper<>();</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // Lambda 语法无需再担心字段写错</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">ge</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(User</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">getAge, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language-sql vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">sql</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Preparing: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SELECT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id,</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,age,email,create_time,update_time,is_delete </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> is_delete</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AND</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (age </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">>=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ?)</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==></span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">)</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Columns: id, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email, create_time, update_time, is_delete</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">28</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Tom@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Sandy, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">21</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Sandy@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Row</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Billie, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">24</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Billie@126.com, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2021</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">01</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">23</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 17</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">47</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">52</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"><==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Total: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=3, name=Tom, age=28, email=Tom@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
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||
<span class="line"><span>User(id=4, name=Sandy, age=21, email=Sandy@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span>
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||
<span class="line"><span>User(id=5, name=Billie, age=24, email=Billie@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span></code></pre></div><h2 id="alleq" tabindex="-1">allEq <a class="header-anchor" href="#alleq" aria-label="Permalink to "allEq""></a></h2><p>最后，笔者再介绍一个比较实用的方法：<code>allEq</code>，当你得到的查询条件都被封装好在一个 Map 集合中时，为了使用 MP 查询这些条件，难道还要一个个的将数据取出来封装为 Wrapper 吗？显然我们是拒绝的。</p><p><code>allEq</code> 可以解决此问题。</p><p><strong>测试代码：</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SpringBootTest</span></span>
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||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusWrapperTests</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Autowired</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UserMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper;</span></span>
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<span class="line"></span>
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||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 需求：查询年龄 = 28 并且姓名为Tom的用户数据</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Test</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testSelectList9</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建查询条件构造器对象，通过泛型指定查询结果类型</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">queryWrapper</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper<>();</span></span>
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<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 模拟一个封装好查询条件的 Map 集合</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Map</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">String</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Object</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">map</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> HashMap<>();</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> map.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">put</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"age"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">28</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> map.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">put</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"name"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">"Tom"</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 将Map直接传给Wrapper的allEq方法，它会自行识别查询条件</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> queryWrapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">allEq</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(map);</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行用户列表查询</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;"><</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">> </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">userList</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userMapper.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">selectList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(queryWrapper);</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 遍历用户列表</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> userList.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.out</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">::</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">println);</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>==> Preparing: SELECT id,name,age,email,create_time,update_time,is_delete FROM user WHERE is_delete=0 AND (name = ? AND age = ?)</span></span>
|
||
<span class="line"><span>==> Parameters: Tom(String), 28(Integer)</span></span>
|
||
<span class="line"><span><== Columns: id, name, age, email, create_time, update_time, is_delete</span></span>
|
||
<span class="line"><span><== Row: 3, Tom, 28, Tom@126.com, 2021-01-23 17:47:52, 2021-01-23 17:47:52, 0</span></span>
|
||
<span class="line"><span><== Total: 1</span></span></code></pre></div><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>User(id=3, name=Tom, age=28, email=Tom@126.com, createTime=2021-01-23T17:47:52, updateTime=2021-01-23T17:47:52, isDelete=0)</span></span></code></pre></div><div class="warning custom-block"><p class="custom-block-title">笔者说</p><p>需要注意的是 <code>allEq()</code> 方法 <strong>只能用于具有 and 关系且都是等值判断的情况</strong> 。</p></div><h2 id="参考文献" tabindex="-1">参考文献 <a class="header-anchor" href="#参考文献" aria-label="Permalink to "参考文献""></a></h2><p>[1]MyBatis Plus 官网. 指南[EB/OL]. <a href="https://baomidou.com/guide/" target="_blank" rel="noreferrer">https://baomidou.com/guide/</a>. 2021-01-18</p><h2 id="后记" tabindex="-1">后记 <a class="header-anchor" href="#后记" aria-label="Permalink to "后记""></a></h2><p><strong>C：</strong> 好了，MP 的条件构造器就介绍完了。笔者有很多 API 没有带大家测试，但我想你也能明白，即便我全部测试了，它也不一定能被你用上，灵活使用它们是需要时间积累的。所以说，讲些典型的，让你 "悟了" MP 的大致规律和节奏，这才是最重要的。</p><p>除了 API 之外，实际上，MP 还有一些功能，因为时间原因，笔者在本次系列并没有提及，你可以前往官网查阅一下，或者等后面笔者时间允许的时候，会再去介绍下它的其他功能。</p><p><strong>最后的最后，笔者个人建议，在日常开发中，如果遇到的需求需要写一个比较复杂的 SQL，那还是直接使用 MyBatis 原生写法去 XML 中写吧，毕竟 MyBatis 最强大的优势还是体现在 XML 的 SQL 中。</strong></p><div class="info custom-block"><p class="custom-block-title">笔者说</p><p>对于技术的学习，笔者一贯遵循的步骤是：先用最最简单的 demo 让它跑起来，然后学学它的最最常用 API 和 配置让自己能用起来，最后熟练使用的基础上，在空闲时尝试阅读它的源码让自己能够洞彻它的运行机制，部分问题出现的原因，同时借鉴这些技术实现来提升自己的代码高度。</p><p>所以在笔者的文章中，前期基本都是小白文，仅仅穿插很少量的源码研究。当然等小白文更新多了，你们还依然喜欢，后期会不定时专门对部分技术的源码进行解析。</p></div></div></div></main><footer class="VPDocFooter" data-v-53ed897c data-v-f3af8004><!--[--><!--[--><!--[--><!--[--><!----><!--]--><!--]--><!--]--><!--]--><div class="edit-info" data-v-f3af8004><div class="edit-link" data-v-f3af8004><a class="VPLink link vp-external-link-icon no-icon edit-link-button" href="https://github.com/Charles7c/charles7c.github.io/edit/main/docs/courses/mybatis/02-MyBatis-Plus基础/04-条件构造器.md" target="_blank" rel="noreferrer" data-v-f3af8004><!--[--><svg xmlns="http://www.w3.org/2000/svg" viewbox="0 0 24 24" class="edit-link-icon" aria-label="edit icon" data-v-f3af8004><path d="M18,23H4c-1.7,0-3-1.3-3-3V6c0-1.7,1.3-3,3-3h7c0.6,0,1,0.4,1,1s-0.4,1-1,1H4C3.4,5,3,5.4,3,6v14c0,0.6,0.4,1,1,1h14c0.6,0,1-0.4,1-1v-7c0-0.6,0.4-1,1-1s1,0.4,1,1v7C21,21.7,19.7,23,18,23z"></path><path d="M8,17c-0.3,0-0.5-0.1-0.7-0.3C7,16.5,6.9,16.1,7,15.8l1-4c0-0.2,0.1-0.3,0.3-0.5l9.5-9.5c1.2-1.2,3.2-1.2,4.4,0c1.2,1.2,1.2,3.2,0,4.4l-9.5,9.5c-0.1,0.1-0.3,0.2-0.5,0.3l-4,1C8.2,17,8.1,17,8,17zM9.9,12.5l-0.5,2.1l2.1-0.5l9.3-9.3c0.4-0.4,0.4-1.1,0-1.6c-0.4-0.4-1.2-0.4-1.6,0l0,0L9.9,12.5z M18.5,2.5L18.5,2.5L18.5,2.5z"></path></svg> 不妥之处，敬请雅正<!--]--></a></div><div class="last-updated" data-v-f3af8004><p class="VPLastUpdated" data-v-f3af8004 data-v-a25eb6f3>最后更新: <time datetime="2022-10-06T10:09:45.000Z" data-v-a25eb6f3></time></p></div></div><nav class="prev-next" data-v-f3af8004><div class="pager" data-v-f3af8004><a class="VPLink link pager-link prev" href="/courses/mybatis/02-MyBatis-Plus%E5%9F%BA%E7%A1%80/03-%E7%AE%80%E5%8D%95%E6%9F%A5%E8%AF%A2%E6%93%8D%E4%BD%9C" data-v-f3af8004><!--[--><span class="desc" data-v-f3af8004>上一篇</span><span class="title" data-v-f3af8004><div class="text-color-yellow mr-[6px]" style="font-weight: 550; display: inline-block;">3</div>简单查询操作</span><!--]--></a></div><div class="pager" data-v-f3af8004><a class="VPLink link pager-link next" href="/courses/mybatis/02-MyBatis-Plus%E5%9F%BA%E7%A1%80/05-%E4%BB%A3%E7%A0%81%E7%94%9F%E6%88%90%E5%99%A8" data-v-f3af8004><!--[--><span class="desc" data-v-f3af8004>下一篇</span><span class="title" data-v-f3af8004><div class="text-color-gray mr-[6px]" style="font-weight: 550; display: inline-block;">5</div>代码生成器</span><!--]--></a></div></nav></footer><!--[--><!--[--><!--[--><div id="comment-container"></div><!--]--><!--]--><!--]--></div></div></div><!--[--><!--]--></div></div><!----><!--[--><!--]--></div></div>
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class=\\\"chinese-zodiac\\\" style=\\\"position: static; vertical-align: middle; padding-bottom: 3px;\\\" src=\\\"/img/svg/chinese-zodiac/tiger.svg\\\" title=\\\"虎年\\\" alt=\\\"生肖\\\">\\n 2022年 (12篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>解决 Maven 传递依赖污染的问题\",\"link\":\"/categories/issues/2022/11/23/解决Maven传递依赖污染的问题\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>解决 DotNet 安装完，报错：Couldn't find a valid ICU package installed on the system. 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Shorten command line for XXX or also for Spring Boot default configuration？\",\"link\":\"/categories/issues/2021/12/10/Command line is too long. 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display: inline-block;\\\">1</div>个人常用快捷键\",\"link\":\"/categories/fragments/2022/10/06/个人常用快捷键\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>个人常用 Git 命令\",\"link\":\"/categories/fragments/2022/10/05/个人常用Git命令\"},{\"text\":\"<div class=\\\"text-color-yellow mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">3</div>个人常用 Docker 命令\",\"link\":\"/categories/fragments/2022/10/01/个人常用Docker命令\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">4</div>个人常用 SQL 函数\",\"link\":\"/categories/fragments/2022/02/16/个人常用SQL函数\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">5</div>个人常用 Linux 命令\",\"link\":\"/categories/fragments/2019/12/31/个人常用Linux命令\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">6</div>个人常用 Hutool 工具类\",\"link\":\"/categories/fragments/2019/12/30/个人常用Hutool工具类\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">7</div>个人常用 Stream 使用技巧\",\"link\":\"/categories/fragments/2019/12/29/个人常用Stream使用技巧\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">8</div>个人 SQL 优化技巧\",\"link\":\"/categories/fragments/2019/12/28/个人SQL优化技巧\"}],\"collapsed\":false},{\"text\":\"<img class=\\\"chinese-zodiac\\\" style=\\\"position: static; vertical-align: middle; padding-bottom: 3px;\\\" src=\\\"/img/svg/chinese-zodiac/rabbit.svg\\\" title=\\\"兔年\\\" alt=\\\"生肖\\\">\\n 2023年 (2篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>一文详解限流接口实现\",\"link\":\"/categories/fragments/2023/12/21/一文详解限流接口实现\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>阿里巴巴的Code Review方法论与实践总结\",\"link\":\"/categories/fragments/2023/01/06/CodeReview方法论与实践总结\"}],\"collapsed\":false},{\"text\":\"<img class=\\\"chinese-zodiac\\\" style=\\\"position: static; vertical-align: middle; padding-bottom: 3px;\\\" src=\\\"/img/svg/chinese-zodiac/tiger.svg\\\" title=\\\"虎年\\\" alt=\\\"生肖\\\">\\n 2022年 (15篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>简单聊聊如何让网站开启灰色显示\",\"link\":\"/categories/fragments/2022/12/07/网站开启灰色显示\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>使用 IntelliJ IDEA 进行远程程序调试\",\"link\":\"/categories/fragments/2022/11/01/使用IDEA进行远程程序调试\"},{\"text\":\"<div class=\\\"text-color-yellow mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">3</div>CentOS 安装 Docker、Docker Compose\",\"link\":\"/categories/fragments/2022/10/31/CentOS安装Docker\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">4</div>Docker 安装 MinIO 详细步骤\",\"link\":\"/categories/fragments/2022/10/28/Docker安装MinIO\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">5</div>Docker 安装 Consul 详细步骤\",\"link\":\"/categories/fragments/2022/10/27/Docker安装Consul\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">6</div>Docker 安装 OpenLDAP 详细步骤\",\"link\":\"/categories/fragments/2022/10/26/Docker安装OpenLDAP\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">7</div>个人常用快捷键\",\"link\":\"/categories/fragments/2022/10/06/个人常用快捷键\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">8</div>个人常用 Git 命令\",\"link\":\"/categories/fragments/2022/10/05/个人常用Git命令\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">9</div>个人常用 Docker 命令\",\"link\":\"/categories/fragments/2022/10/01/个人常用Docker命令\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">10</div>内网CentOS服务器设置网络代理\",\"link\":\"/categories/fragments/2022/08/29/内网CentOS服务器设置网络代理\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">11</div>为指定Git仓库单独配置用户名和邮箱\",\"link\":\"/categories/fragments/2022/03/28/为指定Git仓库单独配置用户名和邮箱\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">12</div>修改Git所有提交记录中的作者和邮箱\",\"link\":\"/categories/fragments/2022/03/27/修改Git所有提交记录中的作者和邮箱\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">13</div>修改Git最后一次提交记录的作者和邮箱\",\"link\":\"/categories/fragments/2022/03/26/修改Git最后一次提交记录的作者和邮箱\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">14</div>合并两个Git仓库的历史提交记录\",\"link\":\"/categories/fragments/2022/03/25/合并两个Git仓库的历史提交记录\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">15</div>个人常用 SQL 函数\",\"link\":\"/categories/fragments/2022/02/16/个人常用SQL函数\"}],\"collapsed\":true},{\"text\":\"<img class=\\\"chinese-zodiac\\\" style=\\\"position: static; vertical-align: middle; padding-bottom: 3px;\\\" src=\\\"/img/svg/chinese-zodiac/ox.svg\\\" title=\\\"牛年\\\" alt=\\\"生肖\\\">\\n 2021年 (2篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>设计模式之单例模式\",\"link\":\"/categories/fragments/2021/05/29/设计模式之单例模式\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>精密计算工具类-BigDecimal\",\"link\":\"/categories/fragments/2021/03/12/精密计算工具类-BigDecimal\"}],\"collapsed\":true},{\"text\":\"<img class=\\\"chinese-zodiac\\\" style=\\\"position: static; vertical-align: middle; padding-bottom: 3px;\\\" src=\\\"/img/svg/chinese-zodiac/pig.svg\\\" title=\\\"猪年\\\" alt=\\\"生肖\\\">\\n 2019年 (4篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>个人常用 Linux 命令\",\"link\":\"/categories/fragments/2019/12/31/个人常用Linux命令\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>个人常用 Hutool 工具类\",\"link\":\"/categories/fragments/2019/12/30/个人常用Hutool工具类\"},{\"text\":\"<div class=\\\"text-color-yellow mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">3</div>个人常用 Stream 使用技巧\",\"link\":\"/categories/fragments/2019/12/29/个人常用Stream使用技巧\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">4</div>个人 SQL 优化技巧\",\"link\":\"/categories/fragments/2019/12/28/个人SQL优化技巧\"}],\"collapsed\":true}],\"/categories/solutions/\":[{\"text\":\"<img class=\\\"chinese-zodiac\\\" style=\\\"position: static; vertical-align: middle; padding-bottom: 3px;\\\" src=\\\"/img/svg/chinese-zodiac/tiger.svg\\\" title=\\\"虎年\\\" alt=\\\"生肖\\\">\\n 2022年 (1篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>递归查询树型结构数据的性能优化方案\",\"link\":\"/categories/solutions/2022/09/07/递归查询树型结构数据的性能优化方案\"}],\"collapsed\":false},{\"text\":\"<img class=\\\"chinese-zodiac\\\" style=\\\"position: static; vertical-align: middle; padding-bottom: 3px;\\\" src=\\\"/img/svg/chinese-zodiac/ox.svg\\\" title=\\\"牛年\\\" alt=\\\"生肖\\\">\\n 2021年 (2篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>一条SQL查询今年每月统计信息\",\"link\":\"/categories/solutions/2021/11/22/一条SQL查询今年每月统计信息\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>用Java8获取近N天日期\",\"link\":\"/categories/solutions/2021/11/18/用Java8获取近N天日期\"}],\"collapsed\":true}],\"/categories/tools/\":[{\"text\":\"<img class=\\\"chinese-zodiac\\\" style=\\\"position: static; vertical-align: middle; padding-bottom: 3px;\\\" src=\\\"/img/svg/chinese-zodiac/ox.svg\\\" title=\\\"牛年\\\" alt=\\\"生肖\\\">\\n 2021年 (5篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>Quartz 快速入门\",\"link\":\"/categories/tools/2021/03/10/Quartz快速入门\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>Postman 快速入门\",\"link\":\"/categories/tools/2021/03/06/Postman快速入门\"},{\"text\":\"<div class=\\\"text-color-yellow mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">3</div>Another Redis Desktop Manager 快速入门\",\"link\":\"/categories/tools/2021/03/04/ARDM快速入门\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">4</div>Redis Desktop Manager 快速入门\",\"link\":\"/categories/tools/2021/02/22/RDM快速入门\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">5</div>初识 Lombok\",\"link\":\"/categories/tools/2021/01/14/初识Lombok\"}],\"collapsed\":false}],\"/courses/java/\":[{\"text\":\"Java语法入门 (14篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>开发环境搭建\",\"link\":\"/courses/java/01-Java语法入门/01-开发环境搭建\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>第一个Java程序\",\"link\":\"/courses/java/01-Java语法入门/02-第一个Java程序\"},{\"text\":\"<div class=\\\"text-color-yellow mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">3</div>初识Eclipse\",\"link\":\"/courses/java/01-Java语法入门/03-初识Eclipse\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">4</div>程序和计算机的那点事儿\",\"link\":\"/courses/java/01-Java语法入门/04-程序和计算机的那点事儿\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">5</div>变量和常量\",\"link\":\"/courses/java/01-Java语法入门/05-变量和常量\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">6</div>常用的运算符\",\"link\":\"/courses/java/01-Java语法入门/06-常用的运算符\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">7</div>控制语句和流程图\",\"link\":\"/courses/java/01-Java语法入门/07-控制语句和流程图\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">8</div>if选择结构\",\"link\":\"/courses/java/01-Java语法入门/08-if选择结构\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">9</div>switch选择结构\",\"link\":\"/courses/java/01-Java语法入门/09-switch选择结构\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">10</div>循环结构\",\"link\":\"/courses/java/01-Java语法入门/10-循环结构\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">11</div>多重循环\",\"link\":\"/courses/java/01-Java语法入门/11-多重循环\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">12</div>程序调试入门\",\"link\":\"/courses/java/01-Java语法入门/12-程序调试入门\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">13</div>一维数组\",\"link\":\"/courses/java/01-Java语法入门/13-一维数组\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">14</div>多维数组\",\"link\":\"/courses/java/01-Java语法入门/14-多维数组\"}],\"collapsed\":false},{\"text\":\"Java面向对象 (1篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>类和对象\",\"link\":\"/courses/java/02-Java面向对象/01-类和对象\"}],\"collapsed\":true},{\"text\":\"Java高级特性 (1篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>集合与泛型-1\",\"link\":\"/courses/java/03-Java高级特性/01-集合与泛型-1\"}],\"collapsed\":true},{\"text\":\"附录 (1篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>CentOS 8.2 安装 JDK 1.8.0_202\",\"link\":\"/courses/java/04-附录/01-CentOS安装JDK\"}],\"collapsed\":true}],\"/courses/mysql/\":[{\"text\":\"MySQL基础 (1篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>MySQL安装与配置\",\"link\":\"/courses/mysql/01-MySQL基础/01-MySQL安装与配置\"}],\"collapsed\":true},{\"text\":\"附录 (2篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>CentOS 8.2 安装 MySQL 5.7.39\",\"link\":\"/courses/mysql/03-附录/01-CentOS安装MySQL\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>Docker 安装 MySQL 详细步骤\",\"link\":\"/courses/mysql/03-附录/02-Docker安装MySQL\"}],\"collapsed\":false}],\"/courses/mybatis/\":[{\"text\":\"MyBatis基础 (8篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">1</div>快速入门\",\"link\":\"/courses/mybatis/01-MyBatis基础/01-快速入门\"},{\"text\":\"<div class=\\\"text-color-orange mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">2</div>核心对象\",\"link\":\"/courses/mybatis/01-MyBatis基础/02-核心对象\"},{\"text\":\"<div class=\\\"text-color-yellow mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">3</div>核心配置文件\",\"link\":\"/courses/mybatis/01-MyBatis基础/03-核心配置文件\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">4</div>SQL映射文件之查询元素\",\"link\":\"/courses/mybatis/01-MyBatis基础/04-SQL映射文件之查询元素\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">5</div>SQL映射文件之增删改元素\",\"link\":\"/courses/mybatis/01-MyBatis基础/05-SQL映射文件之增删改元素\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">6</div>SQL映射文件之自定义映射元素\",\"link\":\"/courses/mybatis/01-MyBatis基础/06-SQL映射文件之自定义映射元素\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">7</div>SQL映射文件之缓存元素\",\"link\":\"/courses/mybatis/01-MyBatis基础/07-SQL映射文件之缓存元素\"},{\"text\":\"<div class=\\\"text-color-gray mr-[6px]\\\" style=\\\"font-weight: 550; display: inline-block;\\\">8</div>动态SQL\",\"link\":\"/courses/mybatis/01-MyBatis基础/08-动态SQL\"}],\"collapsed\":false},{\"text\":\"MyBatis-Plus基础 (5篇)\",\"items\":[{\"text\":\"<div class=\\\"text-color-red mr-[6px]\\\" style=\\\"font-weight: 550; 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