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import{_ as k}from"./chunks/ArticleMetadata.Sb1DYAHo.js";import{_ as p,D as e,o as n,c as r,I as d,w as g,k as h,a as y,R as C,b as A,e as D}from"./chunks/framework.FVQzxbLi.js";import"./chunks/md5.RtphNWHi.js";const F="/assets/202101241302860.fkxfRFWp.jpg",B="/assets/202101241303960.vdvVMZhn.png",c="/assets/202101241303970.gZ8wRV92.gif",M=JSON.parse('{"title":"条件构造器","description":"","frontmatter":{"title":"条件构造器","author":"查尔斯","date":"2021/01/24 13:50","categories":["MyBatis-Plus快速入门"],"tags":["MyBatis Plus","MyBatis","ORM框架"]},"headers":[],"relativePath":"courses/mybatis/02-MyBatis-Plus基础/04-条件构造器.md","filePath":"courses/mybatis/02-MyBatis-Plus基础/04-条件构造器.md","lastUpdated":1665050985000}'),o={name:"courses/mybatis/02-MyBatis-Plus基础/04-条件构造器.md"},E=h("h1",{id:"条件构造器",tabindex:"-1"},[y("条件构造器 "),h("a",{class:"header-anchor",href:"#条件构造器","aria-label":'Permalink to "条件构造器"'},"​")],-1),u=C('<h2 id="前言" tabindex="-1">前言 <a class="header-anchor" href="#前言" aria-label="Permalink to &quot;前言&quot;">​</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&lt;T&gt; updateWrapper) : int</code></li><li><code>delete(Wrapper&lt;T&gt; queryWrapper) : int</code></li><li><code>selectOne(Wrapper&lt;T&gt; queryWrapper) : T</code></li><li><code>selectCount(Wrapper&lt;T&gt; queryWrapper) : Integer</code></li><li><code>selectList(Wrapper&lt;T&gt; queryWrapper) : List&lt;T&gt;</code></li><li><code>selectMaps(Wrapper&lt;T&gt; queryWrapper) : List&lt;Map&lt;String, Object&gt;&gt;</code></li><li><code>selectObjs(Wrapper&lt;T&gt; queryWrapper) : List&lt;Object&gt;</code></li><li><code>selectPage(E page, Wrapper&lt;T&gt; queryWrapper) : E</code></li><li><code>selectMapsPage(E page, Wrapper&lt;T&gt; 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="'+F+'" alt="202101241302860"></p><h2 id="概述" tabindex="-1">概述 <a class="header-anchor" href="#概述" aria-label="Permalink to &quot;概述&quot;">​</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="'+B+'" 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="'+c+`" alt="202101241303970"></p><h2 id="querywrapper" tabindex="-1">QueryWrapper <a class="header-anchor" href="#querywrapper" aria-label="Permalink to &quot;QueryWrapper&quot;">​</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>
<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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">T</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">&gt; </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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">T</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">&gt; {</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;"> /**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 根据 entity 条件，查询全部记录</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> *</span></span>
<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>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> List&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">T</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">&gt; </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&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">T</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">&gt; </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">queryWrapper</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:#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>
<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>
<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>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">FROM</span></span>
<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>
<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>
<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>
<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>
<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>
<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>
<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 &quot;指定查询的列&quot;">​</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&lt;T&gt;</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>
<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 style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
<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>
<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;"> testSelectList1</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 指定查询 name、age 两列数据</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;">&quot;name&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;age&quot;</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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;">==&gt;</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;">==&gt;</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</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;">&quot;DISTINCT name&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;age&quot;</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 &quot;where条件子句&quot;">​</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 &quot;关系运算符&quot;">​</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>&lt;&gt; 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>&gt;</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>&lt;</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>&gt;=</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>&lt;=</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 &gt;= 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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</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;">&quot;age&quot;</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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;">==&gt;</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;">&gt;=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ?)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==&gt;</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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>
<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>
<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 &quot;逻辑运算符&quot;">​</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 &quot;普通逻辑&quot;">​</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&lt;Param&gt; 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&lt;Param&gt; 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&lt;Param&gt; 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 &gt;= 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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</span></span>
<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(&quot;age&quot;, 21);</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // queryWrapper.eq(&quot;name&quot;, &quot;Tom&quot;);</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;">&quot;age&quot;</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 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;">&quot;name&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;Tom&quot;</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;"> // 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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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;">==&gt;</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;">&gt;=</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>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==&gt;</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>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</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;">&quot;age&quot;</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;">&quot;age&quot;</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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;">==&gt;</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;">==&gt;</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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 &quot;嵌套逻辑&quot;">​</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</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;">&quot;name&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;o&quot;</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;">-&gt;</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;">&quot;age&quot;</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;">&quot;name&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;S&quot;</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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;">==&gt;</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>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==&gt;</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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 &quot;范围查询&quot;">​</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>
<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;"> 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>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> QueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</span></span>
<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;">&quot;age&quot;</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>
<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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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;">==&gt;</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>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==&gt;</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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><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 &quot;模糊查询&quot;">​</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 &#39;%A%&#39;</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 &#39;%A%&#39;</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 &#39;%A&#39;</td><td style="text-align:left;">查询</td><td>likeLeft(R column, Object val) : Children</td></tr><tr><td>like &#39;A%&#39;</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>
<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;"> testSelectList6</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</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;">&quot;name&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;o&quot;</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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;">==&gt;</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>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Parameters: %o%(String)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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=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 &quot;分组查询&quot;">​</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(&quot;id&quot;, &quot;name&quot;)</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(&quot;sum(age) &gt; 10&quot;) 例2：having(&quot;sum(age) &gt; {0}&quot;, 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 &quot;排序查询&quot;">​</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(&quot;id&quot;, &quot;name&quot;)</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(&quot;id&quot;, &quot;name&quot;)</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 &quot;连接查询&quot;">​</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 &quot;LambdaQueryWrapper&quot;">​</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>
<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 &gt;= 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;"> testSelectList8</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;"> LambdaQueryWrapper</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</span></span>
<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>
<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>
<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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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;">==&gt;</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;">&gt;=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ?)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">==&gt;</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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;">&lt;==</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>
<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>
<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 &quot;allEq&quot;">​</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>
<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 = 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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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&lt;&gt;();</span></span>
<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;">&lt;</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;">&gt; </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&lt;&gt;();</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;">&quot;age&quot;</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;">&quot;name&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;Tom&quot;</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;">&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">User</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </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>==&gt; 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>==&gt; Parameters: Tom(String), 28(Integer)</span></span>
<span class="line"><span>&lt;== Columns: id, name, age, email, create_time, update_time, is_delete</span></span>
<span class="line"><span>&lt;== 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>&lt;== 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 &quot;参考文献&quot;">​</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 &quot;后记&quot;">​</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 &quot;悟了&quot; 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>`,115);function m(s,b,v,T,q,W){const t=k,l=e("ClientOnly");return n(),r("div",null,[E,d(l,null,{default:g(()=>{var i,a;return[(((i=s.$frontmatter)==null?void 0:i.aside)??!0)&&(((a=s.$frontmatter)==null?void 0:a.showArticleMetadata)??!0)?(n(),A(t,{key:0,article:s.$frontmatter},null,8,["article"])):D("",!0)]}),_:1}),u])}const S=p(o,[["render",m]]);export{M as __pageData,S as default};
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