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的关联查询，数据库表除了前面小节中已经定义好的用户表...","2026-09-12T08:29:57.518395Z",[87],[],{"permalink":412,"excerpt":407,"lastModifyTime":413,"phase":116},"\u002Farchives\u002Fmybaitsplus-join-query","2026-09-13T05:25:32.424638Z",[415],{"metadata":416,"spec":417,"status":418,"postCount":96},{"name":87,"creationTimestamp":88},{"displayName":90,"slug":87,"cover":91,"description":92,"priority":27,"hideFromList":93,"preventParentPostCascadeQuery":93},{"permalink":95,"postCount":96,"visiblePostCount":96},{"metadata":420,"spec":423,"status":432,"categories":436},{"name":421,"creationTimestamp":422},"post-mybaitsplus-enum-value-745dbc08","2026-09-12T08:29:56.730649Z",{"title":424,"slug":425,"cover":426,"excerpt":427,"publishTime":429,"categories":430,"tags":431,"priority":27,"pinned":93,"deleted":93,"visible":111,"allowComment":112},"Mybatis Plus 通用枚举（图文讲解）","mybaitsplus-enum-value","\u002Fupload\u002F167359425246371-MHdo.jpg",{"raw":428,"autoGenerate":93},"\r\n大家好，本小节中，我们将讲解 Mybatis Plus 通用枚举的用法。那么，什么是通用枚举呢？之前小节中，我们的用户表有个性别字段 gender，在插入数据时，我们的示例代码大致如下...","2026-09-12T08:29:56.787230Z",[87],[],{"permalink":433,"excerpt":434,"lastModifyTime":435,"phase":116},"\u002Farchives\u002Fmybaitsplus-enum-value","本小节中，我们将讲解 Mybatis Plus 通用枚举的用法。那么，什么是通用枚举呢？之前小节中，我们的用户表有个性别字段 gender，在插入数据时，我们的示例代码大致如下...","2026-09-13T05:25:33.487169Z",[437],{"metadata":438,"spec":439,"status":440,"postCount":96},{"name":87,"creationTimestamp":88},{"displayName":90,"slug":87,"cover":91,"description":92,"priority":27,"hideFromList":93,"preventParentPostCascadeQuery":93},{"permalink":95,"postCount":96,"visiblePostCount":96},{"metadata":442,"spec":445,"status":454,"categories":458},{"name":443,"creationTimestamp":444},"post-mybaitsplus-common-annotation-80f197dc","2026-09-12T08:29:56.056296Z",{"title":446,"slug":447,"cover":448,"excerpt":449,"publishTime":451,"categories":452,"tags":453,"priority":27,"pinned":93,"deleted":93,"visible":111,"allowComment":112},"Mybatis Plus 常用注解（超详细）","mybaitsplus-common-annotation","\u002Fupload\u002F167334634342163-ZyfL.jpg",{"raw":450,"autoGenerate":93},"大家好，本文主要带大家来看下 Mybatis Plus 框架中，使用频率非常高的几个注解及其属性值，因为编写此本教程目的是为了大家快速入门并使用 Mybatis Plus，关于注解更高级的用法请参考官网...","2026-09-12T08:29:56.114067Z",[87],[],{"permalink":455,"excerpt":456,"lastModifyTime":457,"phase":116},"\u002Farchives\u002Fmybaitsplus-common-annotation","本文主要带大家来看下 Mybatis Plus 框架中，使用频率非常高的几个注解及其属性值，因为编写此本教程目的是为了大家快速入门并使用 Mybatis Plus，关于注解更高级的用法请参考官网...","2026-09-13T05:25:33.983128Z",[459],{"metadata":460,"spec":461,"status":462,"postCount":96},{"name":87,"creationTimestamp":88},{"displayName":90,"slug":87,"cover":91,"description":92,"priority":27,"hideFromList":93,"preventParentPostCascadeQuery":93},{"permalink":95,"postCount":96,"visiblePostCount":96},{"metadata":464,"spec":467,"status":476,"categories":479},{"name":465,"creationTimestamp":466},"post-mybaitsplus-code-generator-c984d27c","2026-09-12T08:29:55.452199Z",{"title":468,"slug":469,"cover":470,"excerpt":471,"publishTime":473,"categories":474,"tags":475,"priority":27,"pinned":93,"deleted":93,"visible":111,"allowComment":112},"Mybatis Plus 代码生成器（图文讲解）","mybaitsplus-code-generator","\u002Fupload\u002F167387297654896-aKtE.jpg",{"raw":472,"autoGenerate":93},"本小节中，我们将学习如何使用 Mybatis Plus 的代码生成器。可能有效小伙伴会疑惑，这玩意是干嘛使的？通常在实际项目开发中，如果开发一个功能，我们会先进行表设计，技术方案的确定，技术经理评估 OK 以后，才会进行项目开发，而不是一上来就写代码，跟无头苍蝇一样...","2026-09-12T08:29:55.508709Z",[87],[],{"permalink":477,"excerpt":472,"lastModifyTime":478,"phase":116},"\u002Farchives\u002Fmybaitsplus-code-generator","2026-09-13T05:25:35.131214Z",[480],{"metadata":481,"spec":482,"status":483,"postCount":96},{"name":87,"creationTimestamp":88},{"displayName":90,"slug":87,"cover":91,"description":92,"priority":27,"hideFromList":93,"preventParentPostCascadeQuery":93},{"permalink":95,"postCount":96,"visiblePostCount":96},{"metadata":485,"spec":486,"status":490,"categories":491,"content":496},{"name":253,"creationTimestamp":254},{"title":256,"slug":257,"cover":258,"excerpt":487,"publishTime":261,"categories":488,"tags":489,"priority":27,"pinned":93,"deleted":93,"visible":111,"allowComment":112},{"raw":260,"autoGenerate":93},[87],[],{"permalink":265,"excerpt":266,"lastModifyTime":267,"phase":116},[492],{"metadata":493,"spec":494,"status":495,"postCount":96},{"name":87,"creationTimestamp":88},{"displayName":90,"slug":87,"cover":91,"description":92,"priority":27,"hideFromList":93,"preventParentPostCascadeQuery":93},{"permalink":95,"postCount":96,"visiblePostCount":96},{"content":497,"raw":498},"\u003Cp>\u003C\u002Fp>\n\u003Cp>本小节中，我们将学习如何通过 Mybatis Plus 删除数据库表中的数据。\u003C\u002Fp>\n\u003Ch2>表结构\u003C\u002Fh2>\n\u003Cp>为了演示删除数据，在前面小节中，我们已经定义好了一个用于测试的用户表， 执行脚本如下：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>DROP TABLE IF EXISTS user;\n\nCREATE TABLE `user` (\n  `id` bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT '主键ID',\n  `name` varchar(30) NOT NULL DEFAULT '' COMMENT '姓名',\n  `age` int(11) NULL DEFAULT NULL COMMENT '年龄',\n  `gender` tinyint(2) NOT NULL DEFAULT 0 COMMENT '性别，0：女 1：男',\n  PRIMARY KEY (`id`)\n) COMMENT = '用户表';\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Ch2>定义实体类\u003C\u002Fh2>\n\u003Cp>定义一个名为 \u003Ccode>User\u003C\u002Fcode> 实体类：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>@TableName("user")\npublic class User {\n    \u002F**\n     * 主键 ID, @TableId 注解定义字段为表的主键，type 表示主键类型，IdType.AUTO 表示随着数据库 ID 自增\n     *\u002F\n    @TableId(type = IdType.AUTO)\n    private Long id;\n    \u002F**\n     * 姓名\n     *\u002F\n    private String name;\n    \u002F**\n     * 年龄\n     *\u002F\n    private Integer age;\n    \u002F**\n     * 性别\n     *\u002F\n    private Integer gender;\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>不明白 Mybatis Plus 实体类注解的小伙伴，可参考前面小节\u003Cspan>\u003Csvg xmlns=\"http:\u002F\u002Fwww.w3.org\u002F2000\u002Fsvg\" style=\"color: #aaa; margin-left: 3px;\" aria-hidden=\"true\" focusable=\"false\" x=\"0px\" y=\"0px\" viewBox=\"0 0 100 100\" width=\"15\" height=\"15\" class=\"icon outbound\">\u003Cpath fill=\"currentColor\" d=\"M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z\">\u003C\u002Fpath> \u003Cpolygon fill=\"currentColor\" points=\"45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9\">\u003C\u002Fpolygon>\u003C\u002Fsvg> \u003Cspan class=\"sr-only\">\u003C\u002Fspan>\u003C\u002Fspan>, 有详细解释。\u003C\u002Fp>\n\u003Ch2>开始删除数据\u003C\u002Fh2>\n\u003Cp>Mybatis Plus 对 Mapper 层和 Service 层都将常见的增删改查操作封装好了，只需简单的继承，即可轻松搞定对数据的增删改查，本文重点讲解删除数据这块。\u003C\u002Fp>\n\u003Ch3>Mapper 层\u003C\u002Fh3>\n\u003Cp>定义一个 \u003Ccode>UserMapper\u003C\u002Fcode> , 让其继承 \u003Ccode>BaseMapper\u003C\u002Fcode> :\u003C\u002Fp>\n\u003Cpre>\u003Ccode>public interface UserMapper extends BaseMapper<User> {\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>然后，注入 Mapper :\u003C\u002Fp>\n\u003Cpre>\u003Ccode>@Autowired\nprivate UserMapper userMapper;\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>删除相关的方法均以 \u003Ccode>delete\u003C\u002Fcode> 开头，方法如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cimg src=\"\u002Fupload\u002F167214854711359-XVkX.jpg\" loading=\"lazy\">\n\u003C\u002Fp>\n\u003Cp>解释一下每个方法的作用：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 根据主键 ID 删除 (直接传入 ID)\nint deleteById(Serializable id);\n\u002F\u002F 根据主键 ID 删除 (传入实体类)\nint deleteById(T entity);\n\u002F\u002F 根据主键 ID 批量删除\nint deleteBatchIds(Collection<?> idList)\n\u002F\u002F 通过 Wrapper 条件构造器删除\nint delete(Wrapper<T> queryWrapper);\n\u002F\u002F 通过 Map 设置条件来删除\nint deleteByMap(Map<String, Object> columnMap);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Ch4>示例代码\u003C\u002Fh4>\n\u003Cp>根据主键 ID 删除 (直接传入 ID)：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 实际执行的 SQL : DELETE FROM user WHERE id=9\nint count = userMapper.deleteById(9L);\nSystem.out.println("受影响的行数:" + count);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>根据主键 ID 删除 (传入实体类)：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>User user = new User();\nuser.setId(9L);\n\u002F\u002F 实际执行的 SQL : DELETE FROM user WHERE id=9\nint count = userMapper.deleteById(user);\nSystem.out.println("受影响的行数:" + count);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>根据主键 ID 批量删除：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 根据 ID 批量删除\nList<Long> ids = new ArrayList<>();\nids.add(1L);\nids.add(2L);\n\n\u002F\u002F 实际执行 SQL 为 ：DELETE FROM user WHERE id IN ( 1 , 2 )\nuserMapper.deleteBatchIds(ids);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>通过 Wrapper 条件构造器删除：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 构造删除条件\nQueryWrapper wrapper = new QueryWrapper<>();\nwrapper.eq("name", "张三1");\nwrapper.eq("age", 1);\n\n\u002F\u002F 实际执行 SQL 为 ：DELETE FROM user WHERE (name = '张三1' AND age = 1)\nuserMapper.delete(wrapper);\n\n\u002F\u002F Lambda 表达式形式\nuserMapper.delete(new QueryWrapper<User>()\n            .lambda()\n            .eq(User::getName, "张三")\n            .eq(User::getAge, 1));\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>通过 Map 设置条件来删除：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 通过 Map 设置条件来删除\nMap<String, Object> columnMap = new HashMap<>();\ncolumnMap.put("name", "张三1");\ncolumnMap.put("age", 1);\n\nint count = userMapper.deleteByMap(columnMap);\nSystem.out.println("受影响的行数:" + count);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>实际执行日志如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cimg src=\"\u002Fupload\u002F167214841959120-WFQB.jpg\" loading=\"lazy\">\n\u003C\u002Fp>\n\u003Ch3>Service 层\u003C\u002Fh3>\n\u003Cp>Mybatis Plus 同样也封装了通用的 Service 层 CRUD 操作，并且提供了更丰富的方法。接下来，我们上手看 Service 层的代码结构，如下图：\u003C\u002Fp>\n\u003Cp>\n\u003Cimg src=\"\u002Fupload\u002F167204808139593-dWMf.jpg\" loading=\"lazy\" title=\"定义 Service 层\" alt=\"定义 Service 层\">\u003Cspan class=\"image-caption\">定义 Service 层\u003C\u002Fspan>\n\u003C\u002Fp>\n\u003Cp>先定义 \u003Ccode>UserService\u003C\u002Fcode> 接口 ，让其继承自 \u003Ccode>IService\u003C\u002Fcode>:\u003C\u002Fp>\n\u003Cpre>\u003Ccode>public interface UserService extends IService<User> {\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>再定义实现类 \u003Ccode>UserServiceImpl\u003C\u002Fcode>，让其继承自 \u003Ccode>ServiceImpl\u003C\u002Fcode>, 同时实现 \u003Ccode>UserService\u003C\u002Fcode> 接口，这样就可以让 \u003Ccode>UserService\u003C\u002Fcode> 拥有了基础通用的 CRUD 功能，当然，实际开发中，业务会更加复杂，就需要向 \u003Ccode>IService\u003C\u002Fcode> 接口自定义方法并实现:\u003C\u002Fp>\n\u003Cpre>\u003Ccode>@Service\npublic class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>注入 \u003Ccode>UserService\u003C\u002Fcode> :\u003C\u002Fp>\n\u003Cpre>\u003Ccode>@Autowired\nprivate UserService userService;\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>Service 层封装的删除方法均以 \u003Ccode>remove\u003C\u002Fcode> 开头，方法如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cimg src=\"\u002Fupload\u002F167215077960978-qJsb.jpg\" loading=\"lazy\">\n\u003C\u002Fp>\n\u003Cp>这里把常用的一些删除方法摘出来：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 根据 entity 条件，删除记录\nboolean remove(Wrapper<T> queryWrapper);\n\u002F\u002F 根据 ID 删除\nboolean removeById(Serializable id);\n\u002F\u002F 根据 columnMap 条件，删除记录\nboolean removeByMap(Map<String, Object> columnMap);\n\u002F\u002F 删除（根据ID 批量删除）\nboolean removeByIds(Collection<? extends Serializable> idList);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>从方法入参可以看出来，和 Mapper 层是删除在使用上基本一样，如何使用可参考 Mapper 层的使用示例代码。\u003C\u002Fp>\n13:T7850,\u003Cp>\u003C\u002Fp>\n\u003Cp>本小节中，我们将学习如何通过 Mybatis Plus 删除数据库表中的数据。\u003C\u002Fp>\n\u003Ch2 id=\"toc-0\">表结构\u003C\u002Fh2>\n\u003Cp>为了演示删除数据，在前面小节中，我们已经定义好了一个用于测试的用户表， 执行脚本如下：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"DROP%20TABLE%20IF%20EXISTS%20user%3B%0A%0ACREATE%20TABLE%20%60user%60%20(%0A%20%20%60id%60%20bigint(20)%20UNSIGNED%20NOT%20NULL%20AUTO_INCREMENT%20COMMENT%20'%E4%B8%BB%E9%94%AEID'%2C%0A%20%20%60name%60%20varchar(30)%20NOT%20NULL%20DEFAULT%20''%20COMMENT%20'%E5%A7%93%E5%90%8D'%2C%0A%20%20%60age%60%20int(11)%20NULL%20DEFAULT%20NULL%20COMMENT%20'%E5%B9%B4%E9%BE%84'%2C%0A%20%20%60gender%60%20tinyint(2)%20NOT%20NULL%20DEFAULT%200%20COMMENT%20'%E6%80%A7%E5%88%AB%EF%BC%8C0%EF%BC%9A%E5%A5%B3%201%EF%BC%9A%E7%94%B7'%2C%0A%20%20PRIMARY%20KEY%20(%60id%60)%0A)%20COMMENT%20%3D%20'%E7%94%A8%E6%88%B7%E8%A1%A8'%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token keyword\">DROP\u003C\u002Fspan> \u003Cspan class=\"token keyword\">TABLE\u003C\u002Fspan> \u003Cspan class=\"token keyword\">IF\u003C\u002Fspan> \u003Cspan class=\"token keyword\">EXISTS\u003C\u002Fspan> \u003Cspan class=\"token keyword\">user\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\n\u003Cspan class=\"token keyword\">CREATE\u003C\u002Fspan> \u003Cspan class=\"token keyword\">TABLE\u003C\u002Fspan> \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>user\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\n  \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>id\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">bigint\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">20\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token keyword\">UNSIGNED\u003C\u002Fspan> \u003Cspan class=\"token operator\">NOT\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">AUTO_INCREMENT\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token string\">'主键ID'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan>\n  \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>name\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">varchar\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">30\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token operator\">NOT\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">DEFAULT\u003C\u002Fspan> \u003Cspan class=\"token string\">''\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token string\">'姓名'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan>\n  \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>age\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">int\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">11\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">DEFAULT\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token string\">'年龄'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan>\n  \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>gender\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">tinyint\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">2\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token operator\">NOT\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">DEFAULT\u003C\u002Fspan> \u003Cspan class=\"token number\">0\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token string\">'性别，0：女 1：男'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan>\n  \u003Cspan class=\"token keyword\">PRIMARY\u003C\u002Fspan> \u003Cspan class=\"token keyword\">KEY\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>id\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token operator\">=\u003C\u002Fspan> \u003Cspan class=\"token string\">'用户表'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Ch2 id=\"toc-1\">定义实体类\u003C\u002Fh2>\n\u003Cp>定义一个名为 \u003Ccode>User\u003C\u002Fcode> 实体类：\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%40TableName(%22user%22)%0Apublic%20class%20User%20%7B%0A%20%20%20%20%2F**%0A%20%20%20%20%20*%20%E4%B8%BB%E9%94%AE%20ID%2C%20%40TableId%20%E6%B3%A8%E8%A7%A3%E5%AE%9A%E4%B9%89%E5%AD%97%E6%AE%B5%E4%B8%BA%E8%A1%A8%E7%9A%84%E4%B8%BB%E9%94%AE%EF%BC%8Ctype%20%E8%A1%A8%E7%A4%BA%E4%B8%BB%E9%94%AE%E7%B1%BB%E5%9E%8B%EF%BC%8CIdType.AUTO%20%E8%A1%A8%E7%A4%BA%E9%9A%8F%E7%9D%80%E6%95%B0%E6%8D%AE%E5%BA%93%20ID%20%E8%87%AA%E5%A2%9E%0A%20%20%20%20%20*%2F%0A%20%20%20%20%40TableId(type%20%3D%20IdType.AUTO)%0A%20%20%20%20private%20Long%20id%3B%0A%20%20%20%20%2F**%0A%20%20%20%20%20*%20%E5%A7%93%E5%90%8D%0A%20%20%20%20%20*%2F%0A%20%20%20%20private%20String%20name%3B%0A%20%20%20%20%2F**%0A%20%20%20%20%20*%20%E5%B9%B4%E9%BE%84%0A%20%20%20%20%20*%2F%0A%20%20%20%20private%20Integer%20age%3B%0A%20%20%20%20%2F**%0A%20%20%20%20%20*%20%E6%80%A7%E5%88%AB%0A%20%20%20%20%20*%2F%0A%20%20%20%20private%20Integer%20gender%3B%0A%7D%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token annotation punctuation\">@TableName\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"user\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">public\u003C\u002Fspan> \u003Cspan class=\"token keyword\">class\u003C\u002Fspan> \u003Cspan class=\"token class-name\">User\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">{\u003C\u002Fspan>\n    \u003Cspan class=\"token comment\">\u002F**\n     * 主键 ID, @TableId 注解定义字段为表的主键，type 表示主键类型，IdType.AUTO 表示随着数据库 ID 自增\n     *\u002F\u003C\u002Fspan>\n    \u003Cspan class=\"token annotation punctuation\">@TableId\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>type \u003Cspan class=\"token operator\">=\u003C\u002Fspan> \u003Cspan class=\"token class-name\">IdType\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token constant\">AUTO\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n    \u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Long\u003C\u002Fspan> id\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n    \u003Cspan class=\"token comment\">\u002F**\n     * 姓名\n     *\u002F\u003C\u002Fspan>\n    \u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">String\u003C\u002Fspan> name\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n    \u003Cspan class=\"token comment\">\u002F**\n     * 年龄\n     *\u002F\u003C\u002Fspan>\n    \u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Integer\u003C\u002Fspan> age\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n    \u003Cspan class=\"token comment\">\u002F**\n     * 性别\n     *\u002F\u003C\u002Fspan>\n    \u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Integer\u003C\u002Fspan> gender\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">}\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>不明白 Mybatis Plus 实体类注解的小伙伴，可参考前面小节\u003Cspan>\u003Csvg xmlns=\"http:\u002F\u002Fwww.w3.org\u002F2000\u002Fsvg\" style=\"color: #aaa; margin-left: 3px;\" aria-hidden=\"true\" focusable=\"false\" x=\"0px\" y=\"0px\" viewBox=\"0 0 100 100\" width=\"15\" height=\"15\" class=\"icon outbound\">\u003Cpath fill=\"currentColor\" d=\"M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z\">\u003C\u002Fpath> \u003Cpolygon fill=\"currentColor\" points=\"45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9\">\u003C\u002Fpolygon>\u003C\u002Fsvg> \u003Cspan class=\"sr-only\">\u003C\u002Fspan>\u003C\u002Fspan>, 有详细解释。\u003C\u002Fp>\n\u003Ch2 id=\"toc-2\">开始删除数据\u003C\u002Fh2>\n\u003Cp>Mybatis Plus 对 Mapper 层和 Service 层都将常见的增删改查操作封装好了，只需简单的继承，即可轻松搞定对数据的增删改查，本文重点讲解删除数据这块。\u003C\u002Fp>\n\u003Ch3 id=\"toc-3\">Mapper 层\u003C\u002Fh3>\n\u003Cp>定义一个 \u003Ccode>UserMapper\u003C\u002Fcode> , 让其继承 \u003Ccode>BaseMapper\u003C\u002Fcode> :\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"public%20interface%20UserMapper%20extends%20BaseMapper%3CUser%3E%20%7B%0A%7D%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token keyword\">public\u003C\u002Fspan> \u003Cspan class=\"token keyword\">interface\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserMapper\u003C\u002Fspan> \u003Cspan class=\"token keyword\">extends\u003C\u002Fspan> \u003Cspan class=\"token class-name\">BaseMapper\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">User\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">{\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">}\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>然后，注入 Mapper :\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%40Autowired%0Aprivate%20UserMapper%20userMapper%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token annotation punctuation\">@Autowired\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserMapper\u003C\u002Fspan> userMapper\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>删除相关的方法均以 \u003Ccode>delete\u003C\u002Fcode> 开头，方法如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cdiv class=\"img-loading\">\u003Cimg src=\"\u002Fupload\u002F167214854711359-XVkX.jpg\" loading=\"lazy\">\u003C\u002Fdiv>\n\u003C\u002Fp>\n\u003Cp>解释一下每个方法的作用：\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%2F%2F%20%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%20ID%20%E5%88%A0%E9%99%A4%20(%E7%9B%B4%E6%8E%A5%E4%BC%A0%E5%85%A5%20ID)%0Aint%20deleteById(Serializable%20id)%3B%0A%2F%2F%20%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%20ID%20%E5%88%A0%E9%99%A4%20(%E4%BC%A0%E5%85%A5%E5%AE%9E%E4%BD%93%E7%B1%BB)%0Aint%20deleteById(T%20entity)%3B%0A%2F%2F%20%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%20ID%20%E6%89%B9%E9%87%8F%E5%88%A0%E9%99%A4%0Aint%20deleteBatchIds(Collection%3C%3F%3E%20idList)%0A%2F%2F%20%E9%80%9A%E8%BF%87%20Wrapper%20%E6%9D%A1%E4%BB%B6%E6%9E%84%E9%80%A0%E5%99%A8%E5%88%A0%E9%99%A4%0Aint%20delete(Wrapper%3CT%3E%20queryWrapper)%3B%0A%2F%2F%20%E9%80%9A%E8%BF%87%20Map%20%E8%AE%BE%E7%BD%AE%E6%9D%A1%E4%BB%B6%E6%9D%A5%E5%88%A0%E9%99%A4%0Aint%20deleteByMap(Map%3CString%2C%20Object%3E%20columnMap)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token comment\">\u002F\u002F 根据主键 ID 删除 (直接传入 ID)\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">deleteById\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Serializable\u003C\u002Fspan> id\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 根据主键 ID 删除 (传入实体类)\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">deleteById\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">T\u003C\u002Fspan> entity\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 根据主键 ID 批量删除\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">deleteBatchIds\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Collection\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token operator\">?\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> idList\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 通过 Wrapper 条件构造器删除\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">delete\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Wrapper\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">T\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> queryWrapper\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 通过 Map 设置条件来删除\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">deleteByMap\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Map\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">String\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Object\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> columnMap\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Ch4 id=\"toc-4\">示例代码\u003C\u002Fh4>\n\u003Cp>根据主键 ID 删除 (直接传入 ID)：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"%2F%2F%20%E5%AE%9E%E9%99%85%E6%89%A7%E8%A1%8C%E7%9A%84%20SQL%20%3A%20DELETE%20FROM%20user%20WHERE%20id%3D9%0Aint%20count%20%3D%20userMapper.deleteById(9L)%3B%0ASystem.out.println(%22%E5%8F%97%E5%BD%B1%E5%93%8D%E7%9A%84%E8%A1%8C%E6%95%B0%3A%22%20%2B%20count)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token comment\">\u002F\u002F 实际执行的 SQL : DELETE FROM user WHERE id=9\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> count \u003Cspan class=\"token operator\">=\u003C\u002Fspan> userMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>deleteById\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">9\u003C\u002Fspan>L\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nSystem\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">out\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>println\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"受影响的行数:\"\u003C\u002Fspan> \u003Cspan class=\"token operator\">+\u003C\u002Fspan> count\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>根据主键 ID 删除 (传入实体类)：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"User%20user%20%3D%20new%20User()%3B%0Auser.setId(9L)%3B%0A%2F%2F%20%E5%AE%9E%E9%99%85%E6%89%A7%E8%A1%8C%E7%9A%84%20SQL%20%3A%20DELETE%20FROM%20user%20WHERE%20id%3D9%0Aint%20count%20%3D%20userMapper.deleteById(user)%3B%0ASystem.out.println(%22%E5%8F%97%E5%BD%B1%E5%93%8D%E7%9A%84%E8%A1%8C%E6%95%B0%3A%22%20%2B%20count)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token keyword\">User\u003C\u002Fspan> \u003Cspan class=\"token keyword\">user\u003C\u002Fspan> \u003Cspan class=\"token operator\">=\u003C\u002Fspan> new \u003Cspan class=\"token keyword\">User\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">user\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>setId\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">9\u003C\u002Fspan>L\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 实际执行的 SQL : DELETE FROM user WHERE id=9\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> count \u003Cspan class=\"token operator\">=\u003C\u002Fspan> userMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>deleteById\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token keyword\">user\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nSystem\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">out\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>println\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"受影响的行数:\"\u003C\u002Fspan> \u003Cspan class=\"token operator\">+\u003C\u002Fspan> count\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>根据主键 ID 批量删除：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"%2F%2F%20%E6%A0%B9%E6%8D%AE%20ID%20%E6%89%B9%E9%87%8F%E5%88%A0%E9%99%A4%0AList%3CLong%3E%20ids%20%3D%20new%20ArrayList%3C%3E()%3B%0Aids.add(1L)%3B%0Aids.add(2L)%3B%0A%0A%2F%2F%20%E5%AE%9E%E9%99%85%E6%89%A7%E8%A1%8C%20SQL%20%E4%B8%BA%20%EF%BC%9ADELETE%20FROM%20user%20WHERE%20id%20IN%20(%201%20%2C%202%20)%0AuserMapper.deleteBatchIds(ids)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token comment\">\u002F\u002F 根据 ID 批量删除\u003C\u002Fspan>\nList\u003Cspan class=\"token operator\"><\u003C\u002Fspan>Long\u003Cspan class=\"token operator\">>\u003C\u002Fspan> ids \u003Cspan class=\"token operator\">=\u003C\u002Fspan> new ArrayList\u003Cspan class=\"token operator\"><>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nids\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">add\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">1\u003C\u002Fspan>L\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nids\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">add\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">2\u003C\u002Fspan>L\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\n\u003Cspan class=\"token comment\">\u002F\u002F 实际执行 SQL 为 ：DELETE FROM user WHERE id IN ( 1 , 2 )\u003C\u002Fspan>\nuserMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>deleteBatchIds\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>ids\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>通过 Wrapper 条件构造器删除：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"%2F%2F%20%E6%9E%84%E9%80%A0%E5%88%A0%E9%99%A4%E6%9D%A1%E4%BB%B6%0AQueryWrapper%20wrapper%20%3D%20new%20QueryWrapper%3C%3E()%3B%0Awrapper.eq(%22name%22%2C%20%22%E5%BC%A0%E4%B8%891%22)%3B%0Awrapper.eq(%22age%22%2C%201)%3B%0A%0A%2F%2F%20%E5%AE%9E%E9%99%85%E6%89%A7%E8%A1%8C%20SQL%20%E4%B8%BA%20%EF%BC%9ADELETE%20FROM%20user%20WHERE%20(name%20%3D%20'%E5%BC%A0%E4%B8%891'%20AND%20age%20%3D%201)%0AuserMapper.delete(wrapper)%3B%0A%0A%2F%2F%20Lambda%20%E8%A1%A8%E8%BE%BE%E5%BC%8F%E5%BD%A2%E5%BC%8F%0AuserMapper.delete(new%20QueryWrapper%3CUser%3E()%0A%20%20%20%20%20%20%20%20%20%20%20%20.lambda()%0A%20%20%20%20%20%20%20%20%20%20%20%20.eq(User%3A%3AgetName%2C%20%22%E5%BC%A0%E4%B8%89%22)%0A%20%20%20%20%20%20%20%20%20%20%20%20.eq(User%3A%3AgetAge%2C%201))%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token comment\">\u002F\u002F 构造删除条件\u003C\u002Fspan>\nQueryWrapper wrapper \u003Cspan class=\"token operator\">=\u003C\u002Fspan> new QueryWrapper\u003Cspan class=\"token operator\"><>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nwrapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>eq\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"name\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token string\">\"张三1\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nwrapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>eq\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"age\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token number\">1\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\n\u003Cspan class=\"token comment\">\u002F\u002F 实际执行 SQL 为 ：DELETE FROM user WHERE (name = '张三1' AND age = 1)\u003C\u002Fspan>\nuserMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">delete\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>wrapper\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\n\u003Cspan class=\"token comment\">\u002F\u002F Lambda 表达式形式\u003C\u002Fspan>\nuserMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">delete\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>new QueryWrapper\u003Cspan class=\"token operator\"><\u003C\u002Fspan>\u003Cspan class=\"token keyword\">User\u003C\u002Fspan>\u003Cspan class=\"token operator\">>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n            \u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>lambda\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n            \u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>eq\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token keyword\">User\u003C\u002Fspan>::getName\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token string\">\"张三\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n            \u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>eq\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token keyword\">User\u003C\u002Fspan>::getAge\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token number\">1\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>通过 Map 设置条件来删除：\u003C\u002Fp>\n\u003Cdiv class=\"language-javascript\" data-ext=\"javascript\" data-code=\"%2F%2F%20%E9%80%9A%E8%BF%87%20Map%20%E8%AE%BE%E7%BD%AE%E6%9D%A1%E4%BB%B6%E6%9D%A5%E5%88%A0%E9%99%A4%0AMap%3CString%2C%20Object%3E%20columnMap%20%3D%20new%20HashMap%3C%3E()%3B%0AcolumnMap.put(%22name%22%2C%20%22%E5%BC%A0%E4%B8%891%22)%3B%0AcolumnMap.put(%22age%22%2C%201)%3B%0A%0Aint%20count%20%3D%20userMapper.deleteByMap(columnMap)%3B%0ASystem.out.println(%22%E5%8F%97%E5%BD%B1%E5%93%8D%E7%9A%84%E8%A1%8C%E6%95%B0%3A%22%20%2B%20count)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-javascript\">\u003Cspan class=\"token comment\">\u002F\u002F 通过 Map 设置条件来删除\u003C\u002Fspan>\nMap\u003Cspan class=\"token operator\"><\u003C\u002Fspan>String\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> Object\u003Cspan class=\"token operator\">>\u003C\u002Fspan> columnMap \u003Cspan class=\"token operator\">=\u003C\u002Fspan> \u003Cspan class=\"token keyword\">new\u003C\u002Fspan> \u003Cspan class=\"token class-name\">HashMap\u003C\u002Fspan>\u003Cspan class=\"token operator\"><\u003C\u002Fspan>\u003Cspan class=\"token operator\">>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\ncolumnMap\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token function\">put\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"name\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token string\">\"张三1\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\ncolumnMap\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token function\">put\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"age\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token number\">1\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\nint count \u003Cspan class=\"token operator\">=\u003C\u002Fspan> userMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token function\">deleteByMap\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>columnMap\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nSystem\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>out\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token function\">println\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"受影响的行数:\"\u003C\u002Fspan> \u003Cspan class=\"token operator\">+\u003C\u002Fspan> count\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>实际执行日志如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cdiv class=\"img-loading\">\u003Cimg src=\"\u002Fupload\u002F167214841959120-WFQB.jpg\" loading=\"lazy\">\u003C\u002Fdiv>\n\u003C\u002Fp>\n\u003Ch3 id=\"toc-5\">Service 层\u003C\u002Fh3>\n\u003Cp>Mybatis Plus 同样也封装了通用的 Service 层 CRUD 操作，并且提供了更丰富的方法。接下来，我们上手看 Service 层的代码结构，如下图：\u003C\u002Fp>\n\u003Cp>\n\u003Cdiv class=\"img-loading\">\u003Cimg src=\"\u002Fupload\u002F167204808139593-dWMf.jpg\" loading=\"lazy\" title=\"定义 Service 层\" alt=\"定义 Service 层\">\u003C\u002Fdiv>\u003Cspan class=\"image-caption\">定义 Service 层\u003C\u002Fspan>\n\u003C\u002Fp>\n\u003Cp>先定义 \u003Ccode>UserService\u003C\u002Fcode> 接口 ，让其继承自 \u003Ccode>IService\u003C\u002Fcode>:\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"public%20interface%20UserService%20extends%20IService%3CUser%3E%20%7B%0A%7D%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token keyword\">public\u003C\u002Fspan> \u003Cspan class=\"token keyword\">interface\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserService\u003C\u002Fspan> \u003Cspan class=\"token keyword\">extends\u003C\u002Fspan> \u003Cspan class=\"token class-name\">IService\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">User\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">{\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">}\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>再定义实现类 \u003Ccode>UserServiceImpl\u003C\u002Fcode>，让其继承自 \u003Ccode>ServiceImpl\u003C\u002Fcode>, 同时实现 \u003Ccode>UserService\u003C\u002Fcode> 接口，这样就可以让 \u003Ccode>UserService\u003C\u002Fcode> 拥有了基础通用的 CRUD 功能，当然，实际开发中，业务会更加复杂，就需要向 \u003Ccode>IService\u003C\u002Fcode> 接口自定义方法并实现:\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%40Service%0Apublic%20class%20UserServiceImpl%20extends%20ServiceImpl%3CUserMapper%2C%20User%3E%20implements%20UserService%20%7B%0A%7D%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token annotation punctuation\">@Service\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">public\u003C\u002Fspan> \u003Cspan class=\"token keyword\">class\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserServiceImpl\u003C\u002Fspan> \u003Cspan class=\"token keyword\">extends\u003C\u002Fspan> \u003Cspan class=\"token class-name\">ServiceImpl\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">UserMapper\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token class-name\">User\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">implements\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserService\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">{\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">}\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>注入 \u003Ccode>UserService\u003C\u002Fcode> :\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%40Autowired%0Aprivate%20UserService%20userService%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token annotation punctuation\">@Autowired\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserService\u003C\u002Fspan> userService\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>Service 层封装的删除方法均以 \u003Ccode>remove\u003C\u002Fcode> 开头，方法如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cdiv class=\"img-loading\">\u003Cimg src=\"\u002Fupload\u002F167215077960978-qJsb.jpg\" loading=\"lazy\">\u003C\u002Fdiv>\n\u003C\u002Fp>\n\u003Cp>这里把常用的一些删除方法摘出来：\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%2F%2F%20%E6%A0%B9%E6%8D%AE%20entity%20%E6%9D%A1%E4%BB%B6%EF%BC%8C%E5%88%A0%E9%99%A4%E8%AE%B0%E5%BD%95%0Aboolean%20remove(Wrapper%3CT%3E%20queryWrapper)%3B%0A%2F%2F%20%E6%A0%B9%E6%8D%AE%20ID%20%E5%88%A0%E9%99%A4%0Aboolean%20removeById(Serializable%20id)%3B%0A%2F%2F%20%E6%A0%B9%E6%8D%AE%20columnMap%20%E6%9D%A1%E4%BB%B6%EF%BC%8C%E5%88%A0%E9%99%A4%E8%AE%B0%E5%BD%95%0Aboolean%20removeByMap(Map%3CString%2C%20Object%3E%20columnMap)%3B%0A%2F%2F%20%E5%88%A0%E9%99%A4%EF%BC%88%E6%A0%B9%E6%8D%AEID%20%E6%89%B9%E9%87%8F%E5%88%A0%E9%99%A4%EF%BC%89%0Aboolean%20removeByIds(Collection%3C%3F%20extends%20Serializable%3E%20idList)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token comment\">\u002F\u002F 根据 entity 条件，删除记录\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">boolean\u003C\u002Fspan> \u003Cspan class=\"token function\">remove\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Wrapper\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">T\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> queryWrapper\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 根据 ID 删除\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">boolean\u003C\u002Fspan> \u003Cspan class=\"token function\">removeById\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Serializable\u003C\u002Fspan> id\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 根据 columnMap 条件，删除记录\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">boolean\u003C\u002Fspan> \u003Cspan class=\"token function\">removeByMap\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Map\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">String\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Object\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> columnMap\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 删除（根据ID 批量删除）\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">boolean\u003C\u002Fspan> \u003Cspan class=\"token function\">removeByIds\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Collection\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token operator\">?\u003C\u002Fspan> \u003Cspan class=\"token keyword\">extends\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Serializable\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> idList\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>从方法入参可以看出来，和 Mapper 层是删除在使用上基本一样，如何使用可参考 Mapper 层的使用示例代码。\u003C\u002Fp>","\u003Cp>大家好。\u003C\u002Fp>\n\u003Cp>本小节中，我们将学习如何通过 Mybatis Plus 删除数据库表中的数据。\u003C\u002Fp>\n\u003Ch2>表结构\u003C\u002Fh2>\n\u003Cp>为了演示删除数据，在前面小节中，我们已经定义好了一个用于测试的用户表， 执行脚本如下：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>DROP TABLE IF EXISTS user;\n\nCREATE TABLE `user` (\n  `id` bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT '主键ID',\n  `name` varchar(30) NOT NULL DEFAULT '' COMMENT '姓名',\n  `age` int(11) NULL DEFAULT NULL COMMENT '年龄',\n  `gender` tinyint(2) NOT NULL DEFAULT 0 COMMENT '性别，0：女 1：男',\n  PRIMARY KEY (`id`)\n) COMMENT = '用户表';\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Ch2>定义实体类\u003C\u002Fh2>\n\u003Cp>定义一个名为 \u003Ccode>User\u003C\u002Fcode> 实体类：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>@TableName("user")\npublic class User {\n    \u002F**\n     * 主键 ID, @TableId 注解定义字段为表的主键，type 表示主键类型，IdType.AUTO 表示随着数据库 ID 自增\n     *\u002F\n    @TableId(type = IdType.AUTO)\n    private Long id;\n    \u002F**\n     * 姓名\n     *\u002F\n    private String name;\n    \u002F**\n     * 年龄\n     *\u002F\n    private Integer age;\n    \u002F**\n     * 性别\n     *\u002F\n    private Integer gender;\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>不明白 Mybatis Plus 实体类注解的小伙伴，可参考前面小节\u003Cspan>\u003Csvg xmlns=\"http:\u002F\u002Fwww.w3.org\u002F2000\u002Fsvg\" style=\"color: #aaa; margin-left: 3px;\" aria-hidden=\"true\" focusable=\"false\" x=\"0px\" y=\"0px\" viewBox=\"0 0 100 100\" width=\"15\" height=\"15\" class=\"icon outbound\">\u003Cpath fill=\"currentColor\" d=\"M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z\">\u003C\u002Fpath> \u003Cpolygon fill=\"currentColor\" points=\"45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9\">\u003C\u002Fpolygon>\u003C\u002Fsvg> \u003Cspan class=\"sr-only\">\u003C\u002Fspan>\u003C\u002Fspan>, 有详细解释。\u003C\u002Fp>\n\u003Ch2>开始删除数据\u003C\u002Fh2>\n\u003Cp>Mybatis Plus 对 Mapper 层和 Service 层都将常见的增删改查操作封装好了，只需简单的继承，即可轻松搞定对数据的增删改查，本文重点讲解删除数据这块。\u003C\u002Fp>\n\u003Ch3>Mapper 层\u003C\u002Fh3>\n\u003Cp>定义一个 \u003Ccode>UserMapper\u003C\u002Fcode> , 让其继承 \u003Ccode>BaseMapper\u003C\u002Fcode> :\u003C\u002Fp>\n\u003Cpre>\u003Ccode>public interface UserMapper extends BaseMapper<User> {\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>然后，注入 Mapper :\u003C\u002Fp>\n\u003Cpre>\u003Ccode>@Autowired\nprivate UserMapper userMapper;\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>删除相关的方法均以 \u003Ccode>delete\u003C\u002Fcode> 开头，方法如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cimg src=\"\u002Fupload\u002F167214854711359-XVkX.jpg\" loading=\"lazy\">\n\u003C\u002Fp>\n\u003Cp>解释一下每个方法的作用：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 根据主键 ID 删除 (直接传入 ID)\nint deleteById(Serializable id);\n\u002F\u002F 根据主键 ID 删除 (传入实体类)\nint deleteById(T entity);\n\u002F\u002F 根据主键 ID 批量删除\nint deleteBatchIds(Collection<?> idList)\n\u002F\u002F 通过 Wrapper 条件构造器删除\nint delete(Wrapper<T> queryWrapper);\n\u002F\u002F 通过 Map 设置条件来删除\nint deleteByMap(Map<String, Object> columnMap);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Ch4>示例代码\u003C\u002Fh4>\n\u003Cp>根据主键 ID 删除 (直接传入 ID)：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 实际执行的 SQL : DELETE FROM user WHERE id=9\nint count = userMapper.deleteById(9L);\nSystem.out.println("受影响的行数:" + count);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>根据主键 ID 删除 (传入实体类)：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>User user = new User();\nuser.setId(9L);\n\u002F\u002F 实际执行的 SQL : DELETE FROM user WHERE id=9\nint count = userMapper.deleteById(user);\nSystem.out.println("受影响的行数:" + count);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>根据主键 ID 批量删除：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 根据 ID 批量删除\nList<Long> ids = new ArrayList<>();\nids.add(1L);\nids.add(2L);\n\n\u002F\u002F 实际执行 SQL 为 ：DELETE FROM user WHERE id IN ( 1 , 2 )\nuserMapper.deleteBatchIds(ids);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>通过 Wrapper 条件构造器删除：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 构造删除条件\nQueryWrapper wrapper = new QueryWrapper<>();\nwrapper.eq("name", "张三1");\nwrapper.eq("age", 1);\n\n\u002F\u002F 实际执行 SQL 为 ：DELETE FROM user WHERE (name = '张三1' AND age = 1)\nuserMapper.delete(wrapper);\n\n\u002F\u002F Lambda 表达式形式\nuserMapper.delete(new QueryWrapper<User>()\n            .lambda()\n            .eq(User::getName, "张三")\n            .eq(User::getAge, 1));\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>通过 Map 设置条件来删除：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 通过 Map 设置条件来删除\nMap<String, Object> columnMap = new HashMap<>();\ncolumnMap.put("name", "张三1");\ncolumnMap.put("age", 1);\n\nint count = userMapper.deleteByMap(columnMap);\nSystem.out.println("受影响的行数:" + count);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>实际执行日志如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cimg src=\"\u002Fupload\u002F167214841959120-WFQB.jpg\" loading=\"lazy\">\n\u003C\u002Fp>\n\u003Ch3>Service 层\u003C\u002Fh3>\n\u003Cp>Mybatis Plus 同样也封装了通用的 Service 层 CRUD 操作，并且提供了更丰富的方法。接下来，我们上手看 Service 层的代码结构，如下图：\u003C\u002Fp>\n\u003Cp>\n\u003Cimg src=\"\u002Fupload\u002F167204808139593-dWMf.jpg\" loading=\"lazy\" title=\"定义 Service 层\" alt=\"定义 Service 层\">\u003Cspan class=\"image-caption\">定义 Service 层\u003C\u002Fspan>\n\u003C\u002Fp>\n\u003Cp>先定义 \u003Ccode>UserService\u003C\u002Fcode> 接口 ，让其继承自 \u003Ccode>IService\u003C\u002Fcode>:\u003C\u002Fp>\n\u003Cpre>\u003Ccode>public interface UserService extends IService<User> {\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>再定义实现类 \u003Ccode>UserServiceImpl\u003C\u002Fcode>，让其继承自 \u003Ccode>ServiceImpl\u003C\u002Fcode>, 同时实现 \u003Ccode>UserService\u003C\u002Fcode> 接口，这样就可以让 \u003Ccode>UserService\u003C\u002Fcode> 拥有了基础通用的 CRUD 功能，当然，实际开发中，业务会更加复杂，就需要向 \u003Ccode>IService\u003C\u002Fcode> 接口自定义方法并实现:\u003C\u002Fp>\n\u003Cpre>\u003Ccode>@Service\npublic class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>注入 \u003Ccode>UserService\u003C\u002Fcode> :\u003C\u002Fp>\n\u003Cpre>\u003Ccode>@Autowired\nprivate UserService userService;\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>Service 层封装的删除方法均以 \u003Ccode>remove\u003C\u002Fcode> 开头，方法如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cimg src=\"\u002Fupload\u002F167215077960978-qJsb.jpg\" loading=\"lazy\">\n\u003C\u002Fp>\n\u003Cp>这里把常用的一些删除方法摘出来：\u003C\u002Fp>\n\u003Cpre>\u003Ccode>\u002F\u002F 根据 entity 条件，删除记录\nboolean remove(Wrapper<T> queryWrapper);\n\u002F\u002F 根据 ID 删除\nboolean removeById(Serializable id);\n\u002F\u002F 根据 columnMap 条件，删除记录\nboolean removeByMap(Map<String, Object> columnMap);\n\u002F\u002F 删除（根据ID 批量删除）\nboolean removeByIds(Collection<? extends Serializable> idList);\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>从方法入参可以看出来，和 Mapper 层是删除在使用上基本一样，如何使用可参考 Mapper 层的使用示例代码。\u003C\u002Fp>\n13:T7850,\u003Cp>大家好。\u003C\u002Fp>\n\u003Cp>本小节中，我们将学习如何通过 Mybatis Plus 删除数据库表中的数据。\u003C\u002Fp>\n\u003Ch2 id=\"toc-0\">表结构\u003C\u002Fh2>\n\u003Cp>为了演示删除数据，在前面小节中，我们已经定义好了一个用于测试的用户表， 执行脚本如下：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"DROP%20TABLE%20IF%20EXISTS%20user%3B%0A%0ACREATE%20TABLE%20%60user%60%20(%0A%20%20%60id%60%20bigint(20)%20UNSIGNED%20NOT%20NULL%20AUTO_INCREMENT%20COMMENT%20'%E4%B8%BB%E9%94%AEID'%2C%0A%20%20%60name%60%20varchar(30)%20NOT%20NULL%20DEFAULT%20''%20COMMENT%20'%E5%A7%93%E5%90%8D'%2C%0A%20%20%60age%60%20int(11)%20NULL%20DEFAULT%20NULL%20COMMENT%20'%E5%B9%B4%E9%BE%84'%2C%0A%20%20%60gender%60%20tinyint(2)%20NOT%20NULL%20DEFAULT%200%20COMMENT%20'%E6%80%A7%E5%88%AB%EF%BC%8C0%EF%BC%9A%E5%A5%B3%201%EF%BC%9A%E7%94%B7'%2C%0A%20%20PRIMARY%20KEY%20(%60id%60)%0A)%20COMMENT%20%3D%20'%E7%94%A8%E6%88%B7%E8%A1%A8'%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token keyword\">DROP\u003C\u002Fspan> \u003Cspan class=\"token keyword\">TABLE\u003C\u002Fspan> \u003Cspan class=\"token keyword\">IF\u003C\u002Fspan> \u003Cspan class=\"token keyword\">EXISTS\u003C\u002Fspan> \u003Cspan class=\"token keyword\">user\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\n\u003Cspan class=\"token keyword\">CREATE\u003C\u002Fspan> \u003Cspan class=\"token keyword\">TABLE\u003C\u002Fspan> \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>user\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\n  \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>id\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">bigint\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">20\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token keyword\">UNSIGNED\u003C\u002Fspan> \u003Cspan class=\"token operator\">NOT\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">AUTO_INCREMENT\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token string\">'主键ID'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan>\n  \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>name\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">varchar\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">30\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token operator\">NOT\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">DEFAULT\u003C\u002Fspan> \u003Cspan class=\"token string\">''\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token string\">'姓名'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan>\n  \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>age\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">int\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">11\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">DEFAULT\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token string\">'年龄'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan>\n  \u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>gender\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">tinyint\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">2\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token operator\">NOT\u003C\u002Fspan> \u003Cspan class=\"token boolean\">NULL\u003C\u002Fspan> \u003Cspan class=\"token keyword\">DEFAULT\u003C\u002Fspan> \u003Cspan class=\"token number\">0\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token string\">'性别，0：女 1：男'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan>\n  \u003Cspan class=\"token keyword\">PRIMARY\u003C\u002Fspan> \u003Cspan class=\"token keyword\">KEY\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token identifier\">\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>id\u003Cspan class=\"token punctuation\">`\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan> \u003Cspan class=\"token keyword\">COMMENT\u003C\u002Fspan> \u003Cspan class=\"token operator\">=\u003C\u002Fspan> \u003Cspan class=\"token string\">'用户表'\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Ch2 id=\"toc-1\">定义实体类\u003C\u002Fh2>\n\u003Cp>定义一个名为 \u003Ccode>User\u003C\u002Fcode> 实体类：\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%40TableName(%22user%22)%0Apublic%20class%20User%20%7B%0A%20%20%20%20%2F**%0A%20%20%20%20%20*%20%E4%B8%BB%E9%94%AE%20ID%2C%20%40TableId%20%E6%B3%A8%E8%A7%A3%E5%AE%9A%E4%B9%89%E5%AD%97%E6%AE%B5%E4%B8%BA%E8%A1%A8%E7%9A%84%E4%B8%BB%E9%94%AE%EF%BC%8Ctype%20%E8%A1%A8%E7%A4%BA%E4%B8%BB%E9%94%AE%E7%B1%BB%E5%9E%8B%EF%BC%8CIdType.AUTO%20%E8%A1%A8%E7%A4%BA%E9%9A%8F%E7%9D%80%E6%95%B0%E6%8D%AE%E5%BA%93%20ID%20%E8%87%AA%E5%A2%9E%0A%20%20%20%20%20*%2F%0A%20%20%20%20%40TableId(type%20%3D%20IdType.AUTO)%0A%20%20%20%20private%20Long%20id%3B%0A%20%20%20%20%2F**%0A%20%20%20%20%20*%20%E5%A7%93%E5%90%8D%0A%20%20%20%20%20*%2F%0A%20%20%20%20private%20String%20name%3B%0A%20%20%20%20%2F**%0A%20%20%20%20%20*%20%E5%B9%B4%E9%BE%84%0A%20%20%20%20%20*%2F%0A%20%20%20%20private%20Integer%20age%3B%0A%20%20%20%20%2F**%0A%20%20%20%20%20*%20%E6%80%A7%E5%88%AB%0A%20%20%20%20%20*%2F%0A%20%20%20%20private%20Integer%20gender%3B%0A%7D%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token annotation punctuation\">@TableName\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"user\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">public\u003C\u002Fspan> \u003Cspan class=\"token keyword\">class\u003C\u002Fspan> \u003Cspan class=\"token class-name\">User\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">{\u003C\u002Fspan>\n    \u003Cspan class=\"token comment\">\u002F**\n     * 主键 ID, @TableId 注解定义字段为表的主键，type 表示主键类型，IdType.AUTO 表示随着数据库 ID 自增\n     *\u002F\u003C\u002Fspan>\n    \u003Cspan class=\"token annotation punctuation\">@TableId\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>type \u003Cspan class=\"token operator\">=\u003C\u002Fspan> \u003Cspan class=\"token class-name\">IdType\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token constant\">AUTO\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n    \u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Long\u003C\u002Fspan> id\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n    \u003Cspan class=\"token comment\">\u002F**\n     * 姓名\n     *\u002F\u003C\u002Fspan>\n    \u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">String\u003C\u002Fspan> name\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n    \u003Cspan class=\"token comment\">\u002F**\n     * 年龄\n     *\u002F\u003C\u002Fspan>\n    \u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Integer\u003C\u002Fspan> age\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n    \u003Cspan class=\"token comment\">\u002F**\n     * 性别\n     *\u002F\u003C\u002Fspan>\n    \u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Integer\u003C\u002Fspan> gender\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">}\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>不明白 Mybatis Plus 实体类注解的小伙伴，可参考前面小节\u003Cspan>\u003Csvg xmlns=\"http:\u002F\u002Fwww.w3.org\u002F2000\u002Fsvg\" style=\"color: #aaa; margin-left: 3px;\" aria-hidden=\"true\" focusable=\"false\" x=\"0px\" y=\"0px\" viewBox=\"0 0 100 100\" width=\"15\" height=\"15\" class=\"icon outbound\">\u003Cpath fill=\"currentColor\" d=\"M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z\">\u003C\u002Fpath> \u003Cpolygon fill=\"currentColor\" points=\"45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9\">\u003C\u002Fpolygon>\u003C\u002Fsvg> \u003Cspan class=\"sr-only\">\u003C\u002Fspan>\u003C\u002Fspan>, 有详细解释。\u003C\u002Fp>\n\u003Ch2 id=\"toc-2\">开始删除数据\u003C\u002Fh2>\n\u003Cp>Mybatis Plus 对 Mapper 层和 Service 层都将常见的增删改查操作封装好了，只需简单的继承，即可轻松搞定对数据的增删改查，本文重点讲解删除数据这块。\u003C\u002Fp>\n\u003Ch3 id=\"toc-3\">Mapper 层\u003C\u002Fh3>\n\u003Cp>定义一个 \u003Ccode>UserMapper\u003C\u002Fcode> , 让其继承 \u003Ccode>BaseMapper\u003C\u002Fcode> :\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"public%20interface%20UserMapper%20extends%20BaseMapper%3CUser%3E%20%7B%0A%7D%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token keyword\">public\u003C\u002Fspan> \u003Cspan class=\"token keyword\">interface\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserMapper\u003C\u002Fspan> \u003Cspan class=\"token keyword\">extends\u003C\u002Fspan> \u003Cspan class=\"token class-name\">BaseMapper\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">User\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">{\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">}\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>然后，注入 Mapper :\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%40Autowired%0Aprivate%20UserMapper%20userMapper%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token annotation punctuation\">@Autowired\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserMapper\u003C\u002Fspan> userMapper\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>删除相关的方法均以 \u003Ccode>delete\u003C\u002Fcode> 开头，方法如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cdiv class=\"img-loading\">\u003Cimg src=\"\u002Fupload\u002F167214854711359-XVkX.jpg\" loading=\"lazy\">\u003C\u002Fdiv>\n\u003C\u002Fp>\n\u003Cp>解释一下每个方法的作用：\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%2F%2F%20%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%20ID%20%E5%88%A0%E9%99%A4%20(%E7%9B%B4%E6%8E%A5%E4%BC%A0%E5%85%A5%20ID)%0Aint%20deleteById(Serializable%20id)%3B%0A%2F%2F%20%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%20ID%20%E5%88%A0%E9%99%A4%20(%E4%BC%A0%E5%85%A5%E5%AE%9E%E4%BD%93%E7%B1%BB)%0Aint%20deleteById(T%20entity)%3B%0A%2F%2F%20%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%20ID%20%E6%89%B9%E9%87%8F%E5%88%A0%E9%99%A4%0Aint%20deleteBatchIds(Collection%3C%3F%3E%20idList)%0A%2F%2F%20%E9%80%9A%E8%BF%87%20Wrapper%20%E6%9D%A1%E4%BB%B6%E6%9E%84%E9%80%A0%E5%99%A8%E5%88%A0%E9%99%A4%0Aint%20delete(Wrapper%3CT%3E%20queryWrapper)%3B%0A%2F%2F%20%E9%80%9A%E8%BF%87%20Map%20%E8%AE%BE%E7%BD%AE%E6%9D%A1%E4%BB%B6%E6%9D%A5%E5%88%A0%E9%99%A4%0Aint%20deleteByMap(Map%3CString%2C%20Object%3E%20columnMap)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token comment\">\u002F\u002F 根据主键 ID 删除 (直接传入 ID)\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">deleteById\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Serializable\u003C\u002Fspan> id\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 根据主键 ID 删除 (传入实体类)\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">deleteById\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">T\u003C\u002Fspan> entity\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 根据主键 ID 批量删除\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">deleteBatchIds\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Collection\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token operator\">?\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> idList\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 通过 Wrapper 条件构造器删除\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">delete\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Wrapper\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">T\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> queryWrapper\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 通过 Map 设置条件来删除\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> \u003Cspan class=\"token function\">deleteByMap\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Map\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">String\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Object\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> columnMap\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Ch4 id=\"toc-4\">示例代码\u003C\u002Fh4>\n\u003Cp>根据主键 ID 删除 (直接传入 ID)：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"%2F%2F%20%E5%AE%9E%E9%99%85%E6%89%A7%E8%A1%8C%E7%9A%84%20SQL%20%3A%20DELETE%20FROM%20user%20WHERE%20id%3D9%0Aint%20count%20%3D%20userMapper.deleteById(9L)%3B%0ASystem.out.println(%22%E5%8F%97%E5%BD%B1%E5%93%8D%E7%9A%84%E8%A1%8C%E6%95%B0%3A%22%20%2B%20count)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token comment\">\u002F\u002F 实际执行的 SQL : DELETE FROM user WHERE id=9\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> count \u003Cspan class=\"token operator\">=\u003C\u002Fspan> userMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>deleteById\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">9\u003C\u002Fspan>L\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nSystem\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">out\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>println\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"受影响的行数:\"\u003C\u002Fspan> \u003Cspan class=\"token operator\">+\u003C\u002Fspan> count\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>根据主键 ID 删除 (传入实体类)：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"User%20user%20%3D%20new%20User()%3B%0Auser.setId(9L)%3B%0A%2F%2F%20%E5%AE%9E%E9%99%85%E6%89%A7%E8%A1%8C%E7%9A%84%20SQL%20%3A%20DELETE%20FROM%20user%20WHERE%20id%3D9%0Aint%20count%20%3D%20userMapper.deleteById(user)%3B%0ASystem.out.println(%22%E5%8F%97%E5%BD%B1%E5%93%8D%E7%9A%84%E8%A1%8C%E6%95%B0%3A%22%20%2B%20count)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token keyword\">User\u003C\u002Fspan> \u003Cspan class=\"token keyword\">user\u003C\u002Fspan> \u003Cspan class=\"token operator\">=\u003C\u002Fspan> new \u003Cspan class=\"token keyword\">User\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">user\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>setId\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">9\u003C\u002Fspan>L\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 实际执行的 SQL : DELETE FROM user WHERE id=9\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">int\u003C\u002Fspan> count \u003Cspan class=\"token operator\">=\u003C\u002Fspan> userMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>deleteById\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token keyword\">user\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nSystem\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">out\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>println\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"受影响的行数:\"\u003C\u002Fspan> \u003Cspan class=\"token operator\">+\u003C\u002Fspan> count\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>根据主键 ID 批量删除：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"%2F%2F%20%E6%A0%B9%E6%8D%AE%20ID%20%E6%89%B9%E9%87%8F%E5%88%A0%E9%99%A4%0AList%3CLong%3E%20ids%20%3D%20new%20ArrayList%3C%3E()%3B%0Aids.add(1L)%3B%0Aids.add(2L)%3B%0A%0A%2F%2F%20%E5%AE%9E%E9%99%85%E6%89%A7%E8%A1%8C%20SQL%20%E4%B8%BA%20%EF%BC%9ADELETE%20FROM%20user%20WHERE%20id%20IN%20(%201%20%2C%202%20)%0AuserMapper.deleteBatchIds(ids)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token comment\">\u002F\u002F 根据 ID 批量删除\u003C\u002Fspan>\nList\u003Cspan class=\"token operator\"><\u003C\u002Fspan>Long\u003Cspan class=\"token operator\">>\u003C\u002Fspan> ids \u003Cspan class=\"token operator\">=\u003C\u002Fspan> new ArrayList\u003Cspan class=\"token operator\"><>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nids\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">add\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">1\u003C\u002Fspan>L\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nids\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">add\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token number\">2\u003C\u002Fspan>L\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\n\u003Cspan class=\"token comment\">\u002F\u002F 实际执行 SQL 为 ：DELETE FROM user WHERE id IN ( 1 , 2 )\u003C\u002Fspan>\nuserMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>deleteBatchIds\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>ids\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>通过 Wrapper 条件构造器删除：\u003C\u002Fp>\n\u003Cdiv class=\"language-sql\" data-ext=\"sql\" data-code=\"%2F%2F%20%E6%9E%84%E9%80%A0%E5%88%A0%E9%99%A4%E6%9D%A1%E4%BB%B6%0AQueryWrapper%20wrapper%20%3D%20new%20QueryWrapper%3C%3E()%3B%0Awrapper.eq(%22name%22%2C%20%22%E5%BC%A0%E4%B8%891%22)%3B%0Awrapper.eq(%22age%22%2C%201)%3B%0A%0A%2F%2F%20%E5%AE%9E%E9%99%85%E6%89%A7%E8%A1%8C%20SQL%20%E4%B8%BA%20%EF%BC%9ADELETE%20FROM%20user%20WHERE%20(name%20%3D%20'%E5%BC%A0%E4%B8%891'%20AND%20age%20%3D%201)%0AuserMapper.delete(wrapper)%3B%0A%0A%2F%2F%20Lambda%20%E8%A1%A8%E8%BE%BE%E5%BC%8F%E5%BD%A2%E5%BC%8F%0AuserMapper.delete(new%20QueryWrapper%3CUser%3E()%0A%20%20%20%20%20%20%20%20%20%20%20%20.lambda()%0A%20%20%20%20%20%20%20%20%20%20%20%20.eq(User%3A%3AgetName%2C%20%22%E5%BC%A0%E4%B8%89%22)%0A%20%20%20%20%20%20%20%20%20%20%20%20.eq(User%3A%3AgetAge%2C%201))%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-sql\">\u003Cspan class=\"token comment\">\u002F\u002F 构造删除条件\u003C\u002Fspan>\nQueryWrapper wrapper \u003Cspan class=\"token operator\">=\u003C\u002Fspan> new QueryWrapper\u003Cspan class=\"token operator\"><>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nwrapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>eq\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"name\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token string\">\"张三1\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nwrapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>eq\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"age\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token number\">1\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\n\u003Cspan class=\"token comment\">\u002F\u002F 实际执行 SQL 为 ：DELETE FROM user WHERE (name = '张三1' AND age = 1)\u003C\u002Fspan>\nuserMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">delete\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>wrapper\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\n\u003Cspan class=\"token comment\">\u002F\u002F Lambda 表达式形式\u003C\u002Fspan>\nuserMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token keyword\">delete\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>new QueryWrapper\u003Cspan class=\"token operator\"><\u003C\u002Fspan>\u003Cspan class=\"token keyword\">User\u003C\u002Fspan>\u003Cspan class=\"token operator\">>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n            \u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>lambda\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n            \u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>eq\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token keyword\">User\u003C\u002Fspan>::getName\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token string\">\"张三\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\n            \u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>eq\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token keyword\">User\u003C\u002Fspan>::getAge\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token number\">1\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>通过 Map 设置条件来删除：\u003C\u002Fp>\n\u003Cdiv class=\"language-javascript\" data-ext=\"javascript\" data-code=\"%2F%2F%20%E9%80%9A%E8%BF%87%20Map%20%E8%AE%BE%E7%BD%AE%E6%9D%A1%E4%BB%B6%E6%9D%A5%E5%88%A0%E9%99%A4%0AMap%3CString%2C%20Object%3E%20columnMap%20%3D%20new%20HashMap%3C%3E()%3B%0AcolumnMap.put(%22name%22%2C%20%22%E5%BC%A0%E4%B8%891%22)%3B%0AcolumnMap.put(%22age%22%2C%201)%3B%0A%0Aint%20count%20%3D%20userMapper.deleteByMap(columnMap)%3B%0ASystem.out.println(%22%E5%8F%97%E5%BD%B1%E5%93%8D%E7%9A%84%E8%A1%8C%E6%95%B0%3A%22%20%2B%20count)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-javascript\">\u003Cspan class=\"token comment\">\u002F\u002F 通过 Map 设置条件来删除\u003C\u002Fspan>\nMap\u003Cspan class=\"token operator\"><\u003C\u002Fspan>String\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> Object\u003Cspan class=\"token operator\">>\u003C\u002Fspan> columnMap \u003Cspan class=\"token operator\">=\u003C\u002Fspan> \u003Cspan class=\"token keyword\">new\u003C\u002Fspan> \u003Cspan class=\"token class-name\">HashMap\u003C\u002Fspan>\u003Cspan class=\"token operator\"><\u003C\u002Fspan>\u003Cspan class=\"token operator\">>\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\ncolumnMap\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token function\">put\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"name\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token string\">\"张三1\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\ncolumnMap\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token function\">put\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"age\"\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token number\">1\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\nint count \u003Cspan class=\"token operator\">=\u003C\u002Fspan> userMapper\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token function\">deleteByMap\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>columnMap\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\nSystem\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>out\u003Cspan class=\"token punctuation\">.\u003C\u002Fspan>\u003Cspan class=\"token function\">println\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token string\">\"受影响的行数:\"\u003C\u002Fspan> \u003Cspan class=\"token operator\">+\u003C\u002Fspan> count\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>实际执行日志如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cdiv class=\"img-loading\">\u003Cimg src=\"\u002Fupload\u002F167214841959120-WFQB.jpg\" loading=\"lazy\">\u003C\u002Fdiv>\n\u003C\u002Fp>\n\u003Ch3 id=\"toc-5\">Service 层\u003C\u002Fh3>\n\u003Cp>Mybatis Plus 同样也封装了通用的 Service 层 CRUD 操作，并且提供了更丰富的方法。接下来，我们上手看 Service 层的代码结构，如下图：\u003C\u002Fp>\n\u003Cp>\n\u003Cdiv class=\"img-loading\">\u003Cimg src=\"\u002Fupload\u002F167204808139593-dWMf.jpg\" loading=\"lazy\" title=\"定义 Service 层\" alt=\"定义 Service 层\">\u003C\u002Fdiv>\u003Cspan class=\"image-caption\">定义 Service 层\u003C\u002Fspan>\n\u003C\u002Fp>\n\u003Cp>先定义 \u003Ccode>UserService\u003C\u002Fcode> 接口 ，让其继承自 \u003Ccode>IService\u003C\u002Fcode>:\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"public%20interface%20UserService%20extends%20IService%3CUser%3E%20%7B%0A%7D%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token keyword\">public\u003C\u002Fspan> \u003Cspan class=\"token keyword\">interface\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserService\u003C\u002Fspan> \u003Cspan class=\"token keyword\">extends\u003C\u002Fspan> \u003Cspan class=\"token class-name\">IService\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">User\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">{\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">}\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>再定义实现类 \u003Ccode>UserServiceImpl\u003C\u002Fcode>，让其继承自 \u003Ccode>ServiceImpl\u003C\u002Fcode>, 同时实现 \u003Ccode>UserService\u003C\u002Fcode> 接口，这样就可以让 \u003Ccode>UserService\u003C\u002Fcode> 拥有了基础通用的 CRUD 功能，当然，实际开发中，业务会更加复杂，就需要向 \u003Ccode>IService\u003C\u002Fcode> 接口自定义方法并实现:\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%40Service%0Apublic%20class%20UserServiceImpl%20extends%20ServiceImpl%3CUserMapper%2C%20User%3E%20implements%20UserService%20%7B%0A%7D%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token annotation punctuation\">@Service\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">public\u003C\u002Fspan> \u003Cspan class=\"token keyword\">class\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserServiceImpl\u003C\u002Fspan> \u003Cspan class=\"token keyword\">extends\u003C\u002Fspan> \u003Cspan class=\"token class-name\">ServiceImpl\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">UserMapper\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token class-name\">User\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> \u003Cspan class=\"token keyword\">implements\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserService\u003C\u002Fspan> \u003Cspan class=\"token punctuation\">{\u003C\u002Fspan>\n\u003Cspan class=\"token punctuation\">}\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>注入 \u003Ccode>UserService\u003C\u002Fcode> :\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%40Autowired%0Aprivate%20UserService%20userService%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token annotation punctuation\">@Autowired\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">private\u003C\u002Fspan> \u003Cspan class=\"token class-name\">UserService\u003C\u002Fspan> userService\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>Service 层封装的删除方法均以 \u003Ccode>remove\u003C\u002Fcode> 开头，方法如下：\u003C\u002Fp>\n\u003Cp>\n\u003Cdiv class=\"img-loading\">\u003Cimg src=\"\u002Fupload\u002F167215077960978-qJsb.jpg\" loading=\"lazy\">\u003C\u002Fdiv>\n\u003C\u002Fp>\n\u003Cp>这里把常用的一些删除方法摘出来：\u003C\u002Fp>\n\u003Cdiv class=\"language-java\" data-ext=\"java\" data-code=\"%2F%2F%20%E6%A0%B9%E6%8D%AE%20entity%20%E6%9D%A1%E4%BB%B6%EF%BC%8C%E5%88%A0%E9%99%A4%E8%AE%B0%E5%BD%95%0Aboolean%20remove(Wrapper%3CT%3E%20queryWrapper)%3B%0A%2F%2F%20%E6%A0%B9%E6%8D%AE%20ID%20%E5%88%A0%E9%99%A4%0Aboolean%20removeById(Serializable%20id)%3B%0A%2F%2F%20%E6%A0%B9%E6%8D%AE%20columnMap%20%E6%9D%A1%E4%BB%B6%EF%BC%8C%E5%88%A0%E9%99%A4%E8%AE%B0%E5%BD%95%0Aboolean%20removeByMap(Map%3CString%2C%20Object%3E%20columnMap)%3B%0A%2F%2F%20%E5%88%A0%E9%99%A4%EF%BC%88%E6%A0%B9%E6%8D%AEID%20%E6%89%B9%E9%87%8F%E5%88%A0%E9%99%A4%EF%BC%89%0Aboolean%20removeByIds(Collection%3C%3F%20extends%20Serializable%3E%20idList)%3B%0A\">\n        \u003Cbutton class=\"vp-copy-code-button\" data-copy data-copied=\"已复制\" aria-label=\"复制代码\">\u003C\u002Fbutton>\n        \u003Cpre>\u003Ccode class=\"language-java\">\u003Cspan class=\"token comment\">\u002F\u002F 根据 entity 条件，删除记录\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">boolean\u003C\u002Fspan> \u003Cspan class=\"token function\">remove\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Wrapper\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">T\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> queryWrapper\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 根据 ID 删除\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">boolean\u003C\u002Fspan> \u003Cspan class=\"token function\">removeById\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Serializable\u003C\u002Fspan> id\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 根据 columnMap 条件，删除记录\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">boolean\u003C\u002Fspan> \u003Cspan class=\"token function\">removeByMap\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Map\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token class-name\">String\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">,\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Object\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> columnMap\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003Cspan class=\"token comment\">\u002F\u002F 删除（根据ID 批量删除）\u003C\u002Fspan>\n\u003Cspan class=\"token keyword\">boolean\u003C\u002Fspan> \u003Cspan class=\"token function\">removeByIds\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">(\u003C\u002Fspan>\u003Cspan class=\"token class-name\">Collection\u003C\u002Fspan>\u003Cspan class=\"token generics\">\u003Cspan class=\"token punctuation\"><\u003C\u002Fspan>\u003Cspan class=\"token operator\">?\u003C\u002Fspan> \u003Cspan class=\"token keyword\">extends\u003C\u002Fspan> \u003Cspan class=\"token class-name\">Serializable\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">>\u003C\u002Fspan>\u003C\u002Fspan> idList\u003Cspan class=\"token punctuation\">)\u003C\u002Fspan>\u003Cspan class=\"token punctuation\">;\u003C\u002Fspan>\n\u003C\u002Fcode>\u003C\u002Fpre>\n      \u003C\u002Fdiv>\n\u003Cp>从方法入参可以看出来，和 Mapper 层是删除在使用上基本一样，如何使用可参考 Mapper 层的使用示例代码。\u003C\u002Fp>"]