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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> interface</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> BaseMapper</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">&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;"> * 插入一条记录</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;"> entity</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 实体对象</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@return</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 影响行数</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> insert</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(T </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">entity</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></code></pre></div><h3 id="插入1条记录" tabindex="-1">插入1条记录 <a class="header-anchor" href="#插入1条记录" aria-label="Permalink to &quot;插入1条记录&quot;">​</a></h3><p>接下来，我们准备测试一下插入操作 API，我们先在上一篇 Demo 项目的基础上，复制粘贴一个专门用于测试 CUD 操作的单元测试类。</p><p><img src="`+B+`" alt="202101190000300"></p><p><strong>测试代码：</strong></p><p>笔者提前准备好了一条测试数据。</p><table><thead><tr><th style="text-align:center;">姓名</th><th style="text-align:center;">年龄</th><th style="text-align:center;">邮箱</th></tr></thead><tbody><tr><td style="text-align:center;">Charles</td><td style="text-align:center;">18</td><td style="text-align:center;"><a href="mailto:charles7c@126.com" target="_blank" rel="noreferrer">charles7c@126.com</a></td></tr></tbody></table><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;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> org.junit.Assert;</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;">SpringBootTest</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> MybatisPlusCUDTests</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 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:#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;"> public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> testInsert</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(){</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建用户对象</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> User</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> User</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">();</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">setName</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;Charles&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">setAge</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;"> user.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">setEmail</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;charles7c@126.com&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;"> // 调用插入操作API</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> rows</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;">insert</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(user);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Assert.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">assertEquals</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;">, rows);</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;"> // MP默认就会自动回填生成的主键</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(user.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">getId</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>
<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;">INSERT INTO</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user ( id, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email ) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">VALUES</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;">1352882704631181313</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Long), Charles(String), </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;">), charles7c@126.com(String)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Updates: </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>1352882704631181313</span></span></code></pre></div><h3 id="id生成策略" tabindex="-1">ID生成策略 <a class="header-anchor" href="#id生成策略" aria-label="Permalink to &quot;ID生成策略&quot;">​</a></h3><p>我们在插入成功后，看到用户的 id 值是一个很长的数值，不仔细看还以为是身份证号呢？其实，这是 MP 默认的主键生成策略：<strong>生成分布式唯一ID</strong> 的锅。</p><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>所谓的分布式唯一ID，简称分布式ID。我们都知道数据库中的每条数据都要定义好一个唯一 ID，像 MySQL 等数据库，提供了主键自增功能，以帮助我们自动生成 1、2、3...这种简单的唯一ID。但随着系统业务越来越复杂，数据库开始分库分表，这种传统的 ID 生成策略在分布式情况下有极大可能出现重复 ID，所以分布式 ID 的概念就诞生了。常见的分布式 ID 解决方案有：Redis生成ID、UUID、Snowflake(雪花算法)等。</p><p>自 MP 3.3.0 开始，主键生成策略默认为：使用 雪花算法 + UUID(不含中划线) 组合而成。</p><p><strong>UUID：</strong> UUID是国际标准化组织（ISO）提出的一个概念，是通用唯一识别码（Universally Unique Identifier）的缩写。在所有空间和时间上被视为唯一的标识，UUID 通常由32个十六进制数字表示，以5个字符组显示，每个字符组以“-”隔开。例如：6db55ec5-ff6f-478a-911d-313de67ed563。</p><p><strong><a href="https://github.com/twitter-archive/snowflake/releases/tag/snowflake-2010" target="_blank" rel="noreferrer">Snowflake</a>：</strong> Snowflake 是 Twitter 开源的分布式ID生成算法，结果是一个 long 型的 ID。</p></div><p>如果我们的需求不需要分布式ID，可以替换成 MP 中其他的主键生成策略。我们可以通过查看 MP 的 ID 类型枚举类源码，来查看它有哪些主键生成策略。</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;">/**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 生成ID类型枚举类</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;">@author</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> hubin</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@since</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 2015-11-10</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;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Getter</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> enum</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> IdType</span><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;"> * 数据库ID自增</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 该类型请确保数据库支持并设置了主键自增 否则无效</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> AUTO</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</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;"> /**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 该类型为未设置主键类型(注解里等于跟随全局,全局里约等于 INPUT)</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> NONE</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;">),</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;"> * 用户输入ID</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 该类型可以通过自己注册自动填充插件进行填充</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> INPUT</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</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;"> /* 注意：以下类型、只有当插入对象ID 为空，才自动填充。 */</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;"> * 【MP 默认采用此种主键生成策略】</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 通过雪花算法分配ID (主键类型为数值或字符串),</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@since</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 3.3.0 (3.3.0版本新增该策略)</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> ASSIGN_ID</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;">),</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;"> * 通过UUID分配ID (主键类型为字符串)</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> ASSIGN_UUID</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;">),</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;"> /* ---------已过时，不建议采用--------- */</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;"> * 从3.3.0版本开始过时，可使用ASSIGN_ID替代</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;"> @</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">Deprecated</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ID_WORKER(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><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;"> * 从3.3.0版本开始过时，可使用ASSIGN_ID替代</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;"> @</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">Deprecated</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> ID_WORKER_STR(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><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;"> * 从3.3.0版本开始过时，可使用ASSIGN_UUID替代</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;"> @</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">Deprecated</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> UUID(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> final</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> key;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> IdType</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;"> key</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> this</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.key </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> key;</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>当你看中了某一个生成策略，想来改变默认的主键生成策略时，直接在对应实体类的主键属性上，添加 <code>@TableId</code> 注解即可。</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:#24292E;--shiki-dark:#ADBAC7;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Data</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> User</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;"> // @TableId是用于标注主键属性的注解</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // value：数据表对应的列名，如果实体类属性和数据表列名不一致时使用</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // type：主键生成策略类型</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">TableId</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">type</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> IdType.AUTO)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Long</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> name;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> age;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> email;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p>当然，如果你每个实体都要更改主键生成策略，最好的方式还是直接在 <code>application.yml</code> 中进行全局配置。</p><div class="language-yaml vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">yaml</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;"># MyBatis Plus配置</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;">mybatis-plus</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> # 全局配置</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;"> global-config</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;"> db-config</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> # 主键生成策略</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;"> id-type</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">auto</span></span></code></pre></div><div class="warning custom-block"><p class="custom-block-title">笔者说</p><p>上方的两种配置，如果你选择了全局配置， <strong>就不需要再配置第一种了</strong> 。</p></div><p>更改了主键生成策略后，别忘了先 Truncate 再 Insert 来重置下当前的用户表数据，否则再测试插入时，数据库主键自增序列是从当前的 ID 最大值开始的。</p><p><img src="`+o+`" alt="202101190000400"></p><p>重置完成后，我们再去测试一下刚才的插入操作。</p><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;">INSERT INTO</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user ( </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, age, email ) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">VALUES</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: Charles(String), </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;">), charles7c@126.com(String)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Updates: </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>6</span></span></code></pre></div><p>很显然，这一次，MP 不再为我们分配 ID 了，而是由数据库进行主键自增生成的 ID。</p><h2 id="修改操作" tabindex="-1">修改操作 <a class="header-anchor" href="#修改操作" aria-label="Permalink to &quot;修改操作&quot;">​</a></h2><p>在 BaseMapper 接口中，修改操作的 API 有两个，但本篇我们先只介绍一个，另一个需要等我们学完下一篇的条件构造器再介绍。</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 ID 修改</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;"> entity</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 实体对象</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@return</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 影响行数</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> updateById</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.ENTITY) T </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">entity</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;"> /**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 根据 whereEntity 条件，更新记录</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;"> entity</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 实体对象 (set 条件值,可以为 null)</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;"> updateWrapper</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 实体对象封装操作类（可以为 null,里面的 entity 用于生成 where 语句）</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@return</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 影响行数</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> update</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.ENTITY) T </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">entity</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;">updateWrapper</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><h3 id="根据id修改" tabindex="-1">根据ID修改 <a class="header-anchor" href="#根据id修改" aria-label="Permalink to &quot;根据ID修改&quot;">​</a></h3><p>为了测试修改操作 API，笔者也提前准备好了一条测试数据。</p><table><thead><tr><th style="text-align:center;">主键</th><th style="text-align:center;">姓名</th><th style="text-align:center;">年龄</th><th style="text-align:center;">邮箱</th></tr></thead><tbody><tr><td style="text-align:center;"><strong>5</strong></td><td style="text-align:center;">Billie</td><td style="text-align:center;"><strong>18</strong></td><td style="text-align:center;"><a href="mailto:Billie@126.com" target="_blank" rel="noreferrer">Billie@126.com</a></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;"> MybatisPlusCUDTests</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 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:#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;"> testUpdateById</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(){</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 创建用户对象</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> User</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> User</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">();</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">setId</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5L</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">setAge</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>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行修改操作 API</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> rows</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;">updateById</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(user);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Assert.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">assertEquals</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;">, rows);</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;">UPDATE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SET</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;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id</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;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Long)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Updates: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span></span></code></pre></div><h3 id="自动填充" tabindex="-1">自动填充 <a class="header-anchor" href="#自动填充" aria-label="Permalink to &quot;自动填充&quot;">​</a></h3><p>我们在项目开发过程中，经常要在最终存储数据前，进行一些数据填充工作，例如审计信息：创建人、创建时间，更新人、更新时间等。</p><p>这些数据的填充工作，重复且枯燥，有时候还容易忘记，MP 中提供了自动填充功能，可以结束这类问题。</p><p>接下来，我们就以自动填充实体类的 创建时间、更新时间 这两个属性为例来演示一下 MP 的自动填充功能。</p><p><strong>第1步：我们需要给实体类、数据库表先做一些结构调整工作。</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:#6A737D;--shiki-dark:#768390;">-- 给用户表添加 create_time 和 update_time 两个列</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">ALTER</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> TABLE</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> \`mybatisplus_demodb\`</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">\`user\`</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">ADD</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> COLUMN </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">\`create_time\`</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> datetime</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">NULL</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> COMMENT </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;创建时间&#39;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AFTER</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> \`email\`</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">,</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">ADD</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> COLUMN </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">\`update_time\`</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> datetime</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">NULL</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> COMMENT </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;更新时间&#39;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AFTER</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> \`create_time\`</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span></code></pre></div><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;">Data</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> User</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:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Long</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> name;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> age;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> email;</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 添加对应的实体属性：createTime、updateTime</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> LocalDateTime</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> createTime;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> LocalDateTime</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> updateTime;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>第2步：在 User 类中添加 @TableField 注解来给属性指定自动填充类型。</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;">Data</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> User</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:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Long</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> name;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> age;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> email;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // @TableField是用于标注普通属性的注解</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // value：数据表对应的列名，如果实体类属性和数据表列名不一致时使用</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // fill：自动填充类型</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // INSERT：插入时自动填充</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // UPDATE：更新时自动填充</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // INSERT_UPDATE：插入或更新时自动填充</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">TableField</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">fill</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> FieldFill.INSERT)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> LocalDateTime</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> createTime;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">TableField</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">fill</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> FieldFill.INSERT_UPDATE)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> LocalDateTime</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> updateTime;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>第3步：创建自动审计处理器，实现元对象处理器接口。</strong></p><p><code>com.baomidou.mybatisplus.core.handlers.MetaObjectHandler</code></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;">/**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 通过 MP 的自动填充功能实现自动审计</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;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Component</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> AutoAuditHandler</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> implements</span><span style="--shiki-light:#6F42C1;--shiki-dark:#6CB6FF;"> MetaObjectHandler</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;">Override</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> insertFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(MetaObject </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">metaObject</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> this</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">strictInsertFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(metaObject, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;createTime&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, LocalDateTime.class, LocalDateTime.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">now</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 起始版本 3.3.0(推荐使用)</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> this</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">strictInsertFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(metaObject, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;updateTime&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, LocalDateTime.class, LocalDateTime.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">now</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 起始版本 3.3.0(推荐使用)</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 style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Override</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> updateFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(MetaObject </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">metaObject</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> this</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">setFieldValByName</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;updateTime&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, LocalDateTime.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">now</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(), metaObject);</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>这么做完之后，我们再来测试下刚才的修改操作。</p><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;">UPDATE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SET</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;">?, update_time</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;">WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id</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;">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:#24292E;--shiki-dark:#ADBAC7;">23T16:</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">51</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;">413</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(LocalDateTime), </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Long)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Updates: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span></span></code></pre></div><p>显而易见，执行的 SQL 中多了一个更新时间的修改，而且传的值是当前时间。</p><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>你也可以测试一下刚才的插入操作 API，看看新增数据时是否会自动填充 创建时间 和 更新时间 数据。</p></div><h2 id="删除操作" tabindex="-1">删除操作 <a class="header-anchor" href="#删除操作" aria-label="Permalink to &quot;删除操作&quot;">​</a></h2><p>在 BaseMapper 接口中，删除操作的 API 一共有4个，我们本篇主要介绍一下前三个，最后一个同样也在下一篇再进行介绍。</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:#6A737D;--shiki-dark:#768390;"> /**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 根据 ID 删除</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;"> id</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 主键ID</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@return</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 影响行数</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> deleteById</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Serializable </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">id</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;"> /**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 删除（根据ID 批量删除）</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;"> idList</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 主键ID列表(不能为 null 以及 empty)</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@return</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 影响行数</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> deleteBatchIds</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.COLLECTION) Collection&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">?</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> extends</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> Serializable</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">&gt; </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">idList</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;"> /**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 根据 columnMap 条件，删除记录</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;"> columnMap</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 表字段 map 对象</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@return</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 影响行数</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> deleteByMap</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.COLUMN_MAP) Map&lt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Object</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">&gt; </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">columnMap</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;"> /**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 根据 entity 条件，删除记录</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,里面的 entity 用于生成 where 语句）</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">@return</span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> 影响行数</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> */</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> delete</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><h3 id="根据id删除" tabindex="-1">根据ID删除 <a class="header-anchor" href="#根据id删除" aria-label="Permalink to &quot;根据ID删除&quot;">​</a></h3><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;"> MybatisPlusCUDTests</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 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:#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;"> testDeleteById</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行删除操作API，删除ID为1的用户数据</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> rows</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;">deleteById</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1L</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Assert.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">assertEquals</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;">, rows);</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;">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;"> id</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;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Long)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Updates: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span></span></code></pre></div><h3 id="批量id删除" tabindex="-1">批量ID删除 <a class="header-anchor" href="#批量id删除" aria-label="Permalink to &quot;批量ID删除&quot;">​</a></h3><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;"> MybatisPlusCUDTests</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 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:#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;"> testDeleteBatchIds</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 删除ID为2、3的用户数据</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;">Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">&gt; </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">ids</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Arrays.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">asList</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</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;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> rows</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;">deleteBatchIds</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(ids);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Assert.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">assertEquals</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, rows);</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;">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;"> id </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;">2</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;">3</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;"> Updates: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span></span></code></pre></div><h3 id="简单的带条件删除" tabindex="-1">简单的带条件删除 <a class="header-anchor" href="#简单的带条件删除" aria-label="Permalink to &quot;简单的带条件删除&quot;">​</a></h3><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;"> MybatisPlusDemoApplication</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 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:#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;"> testDeleteByMap</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 删除姓名为Sandy的用户数据</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // Map集合的键：表示的是数据库列名不是实体类属性名</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;">columnMap</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;"> columnMap.</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;Sandy&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> rows</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;">deleteByMap</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(columnMap);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Assert.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">assertEquals</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;">, rows);</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;">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:#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: Sandy(String)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Updates: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span></span></code></pre></div><h3 id="逻辑删除" tabindex="-1">逻辑删除 <a class="header-anchor" href="#逻辑删除" aria-label="Permalink to &quot;逻辑删除&quot;">​</a></h3><p>在项目开发过程中，为了保留用户数据，在删除用户数据时，我们会选择逻辑删除，而非物理删除。</p><ul><li><p><strong>物理删除：</strong> 真实删除，将对应数据从数据库中删除，即采用 <code>delete</code> SQL。</p></li><li><p><strong>逻辑删除：</strong> 假删除，将对应数据中代表是否被删除的列，修改为 &quot;被删除状态值&quot;，即采用 <code>update</code> SQL。</p></li></ul><p>接下来，我们也实现一下逻辑删除功能。</p><p><strong>第1步：我们需要给实体类、数据库表先做一些结构调整工作。</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:#6A737D;--shiki-dark:#768390;">-- 给用户表添加 is_delete 列</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">ALTER</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> TABLE</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> \`mybatisplus_demodb\`</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">\`user\`</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">ADD</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> COLUMN </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">\`is_delete\`</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">NULL</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> COMMENT </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;是否被删除&#39;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> AFTER</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> \`update_time\`</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span></code></pre></div><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;">Data</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> User</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:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Long</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> name;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> age;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> email;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">TableField</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">fill</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> FieldFill.INSERT)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> LocalDateTime</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> createTime;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">TableField</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">fill</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> FieldFill.INSERT_UPDATE)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> LocalDateTime</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> updateTime;</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;"> // 添加对应的实体属性：isDelete</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 为 逻辑删除 属性指定插入数据时自动填充，并调整好数据填充处理器</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">TableField</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">fill</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> FieldFill.INSERT)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> private</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Integer</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> isDelete;</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><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;">/**</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> * 通过 MP 的自动填充功能实现自动审计</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;">@</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Component</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> AutoAuditHandler</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> implements</span><span style="--shiki-light:#6F42C1;--shiki-dark:#6CB6FF;"> MetaObjectHandler</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;">Override</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> insertFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(MetaObject </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">metaObject</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> this</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">strictInsertFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(metaObject, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;createTime&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, LocalDateTime.class, LocalDateTime.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">now</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">());</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> this</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">strictInsertFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(metaObject, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;updateTime&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, LocalDateTime.class, LocalDateTime.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">now</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">()); </span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 插入数据时，逻辑删除属性自动填充值</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> this</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">strictInsertFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(metaObject, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;isDelete&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, Integer.class, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</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>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> @</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">Override</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> updateFill</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(MetaObject </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">metaObject</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> this</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">setFieldValByName</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;updateTime&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, LocalDateTime.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">now</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(), metaObject);</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>第2步：在 application.yml 中，全局配置逻辑删除的默认值和删除值。</strong></p><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>这一步也可以通过在 逻辑删除 属性上方添加 <code>@TableLogic</code> 注解实现，但还是建议采用全局配置。</p></div><div class="language-yaml vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">yaml</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;">mybatis-plus</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;"> global-config</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;"> db-config</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">:</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> # 逻辑删除属性</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;"> logic-delete-field</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">isDelete</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> # 未删除状态值</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;"> logic-not-delete-value</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:#6A737D;--shiki-dark:#768390;"> # 删除状态值</span></span>
<span class="line"><span style="--shiki-light:#22863A;--shiki-dark:#8DDB8C;"> logic-delete-value</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span></span></code></pre></div><p>配置完后，我们再去测试一下刚才的 根据ID删除 操作。</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;"> MybatisPlusCUDTests</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:#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;"> testDeleteById</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">() {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 执行删除操作API，删除ID为5的用户数据</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> rows</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;">deleteById</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5L</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // int rows = userMapper.deleteById(1L);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Assert.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">assertEquals</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;">, rows);</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;">UPDATE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SET</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;">1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id</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:#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:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Long)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Updates: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</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>java.lang.AssertionError: expected:&lt;1&gt; but was:&lt;0&gt;</span></span>
<span class="line"><span>Expected :1</span></span>
<span class="line"><span>Actual :0</span></span></code></pre></div><p>这次执行单元测试，竟然报错了！仔细看一下，原来是 <code>断言</code> 提示我们实际结果和预期结果不一致。</p><p>什么原因导致失败呢？其实是因为我们加入逻辑删除列之后，数据库表中虽然多了这列，但是这一列都还没有设置过值呢。</p><p><img src="`+E+'" alt="202101190000500"></p><p>而执行的 SQL 中却需要查找逻辑删除列值为0的数据，这肯定找不到啊，影响行数自然为 0 了，和我们预期的影响行数 1 不符，于是报错了。</p><p>知道原因后，那就先手动，给数据表的逻辑删除列都设置为0。</p><p><img src="'+u+`" alt="202101190000600"></p><p>再去执行一次刚才的删除测试。</p><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;">UPDATE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> user </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">SET</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;">1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> WHERE</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> id</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:#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:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Long)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;==</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Updates: </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span></span></code></pre></div><p>这回就不再报错了，而且显而易见，执行的 SQL 由没有做逻辑删除配置前的 <code>DELETE</code> 操作现在变为了 <code>UPDATE</code> 操作。</p><p><img src="`+m+'" alt="202101190000700"></p><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>在逻辑删除配置好之后，原来的部分操作，像查询操作，在执行 SQL 时将自动带上 <code>where is_delete = 0</code> 这个条件。</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> 学习 MyBatis 的时候，我们就没担心过 CUD，现在 MP 中自然更不存在这事儿了。而且 MP 还给我们提供了这么多实用功能。</p><p>下一篇我们将会学到较为复杂的查询操作，但 MP 还是相对简单的，敬请期待吧。</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>',117);function T(s,P,M,q,_,U){const p=t,h=e("ClientOnly");return n(),r("div",null,[v,d(h,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(),D(p,{key:0,article:s.$frontmatter},null,8,["article"])):C("",!0)]}),_:1}),I])}const O=k(b,[["render",T]]);export{j as __pageData,O as default};
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