MybatisPlus 常用写法

maven配置

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<!--mybatis-plus-->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.5.5</version>
</dependency>
<!-- 连表查询依赖	-->
<dependency>
    <groupId>com.github.yulichang</groupId>
    <artifactId>mybatis-plus-join-boot-starter</artifactId>
    <version>1.4.6</version>
</dependency>
<!-- 连表查询依赖	-->
<dependency>
    <groupId>com.github.yulichang</groupId>
    <artifactId>mybatis-plus-join-annotation</artifactId>
    <version>1.4.6</version>
</dependency>

新增

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// 直接保存
    sysuserService.save(sysuser);
// 根据是否有主键id更新或保存
sysuserService.saveOrUpdate(sysuser);
// 批量保存
sysuserService.saveBatch(new ArrayList<Sysuser>());

删除

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// 根据id删除
sysuserService.removeById(sysuser);
// 自定义根据条件删除
sysuserService.remove(new LambdaQueryWrapper<Sysuser>()
        .eq(Sysuser::getId, sysuser.getId())
        .or()
        .eq(Sysuser::getMark, sysuser.getMark()));

更新

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// 根据是否有主键id更新
   sysuserService.updateById(sysuser);
   // 自定义根据条件更新
   sysuserService.update(Wrappers.<Sysuser>lambdaUpdate()
           .set(Sysuser::getDelstatus, sysuser.getDelstatus())
           .eq(Sysuser::getId, sysuser.getId()));
   // 批量更新
   sysuserService.updateBatchById(new ArrayList<Sysuser>());

查询

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// 根据id查找
   Sysuser user = sysuserService.getById(sysuser.getId());
   // 根据条件查询
   Sysuser user1 = sysuserService.getOne(new LambdaQueryWrapper<Sysuser>()
           .eq(Sysuser::getUname, sysuser.getUname())
           .eq(StringUtils.isNotBlank(upass),Sysuser::getUpass, upass) //判断密码是否为空
           .eq(Sysuser::getType, "会员")
   );
   // 关联查询
   Sysuser user2 = sysuserService.getOne(new MPJLambdaWrapper<Sysuser>()
           .eq(Sysuser::getUname, sysuser.getUname())
           .eq(Sysuser::getUpass, upass)
           .eq(Sysuser::getType, "会员")
           .leftJoin(Car.class, Car::getId, Sysuser::getId)
           .selectAll(Car.class)
           .selectAs(Car::getId, Sysuser::getUname)
           .selectAs(Car::getId, "carId")
   );
   // 查多个
   List<Sysuser> 会员 = sysuserService.list(new LambdaQueryWrapper<Sysuser>()
           .eq(Sysuser::getUname, sysuser.getUname())
           .eq(Sysuser::getUpass, upass)
           .eq(Sysuser::getType, "会员")
   );
   // 分页查多个
   Page<Sysuser> 会员1 = sysuserService.page(new Page<>(1, 10), new LambdaQueryWrapper<Sysuser>()
           .eq(Sysuser::getUname, sysuser.getUname())
           .eq(Sysuser::getUpass, upass)
           .eq(Sysuser::getType, "会员"));