使用MyBatis Plus的QueryWrapper实现复杂的SQL查询

QueryWrapper<SysUser> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("del_flag", "0")
            .and(wrapper -> wrapper.like("user_name", "粥").or().like("nick_name", "粥"))
            .in("user_id", Arrays.asList(1892512443619762178L, 1892565898380111873L))
            .ne("user_id", 1)
            .eq("tenant_id", "000000");

List<SysUser> userList = sysUserMapper.selectList(queryWrapper);

代码说明：
eq(“del_flag”, “0”) 对应 SQL 中的 u.del_flag = ‘0’

and(wrapper -> wrapper.like(“user_name”, “粥”).or().like(“nick_name”, “粥”)) 对应 (u.user_name LIKE ‘%粥%’ OR u.nick_name LIKE ‘%粥%’)

in(“user_id”, Arrays.asList(…)) 对应 u.user_id IN (1892512443619762178, 1892565898380111873)

ne(“user_id”, 1) 对应 u.user_id <> 1

eq(“tenant_id”, “000000”) 对应 u.tenant_id = ‘000000’

注意事项：
确保SysUser实体类中的属性与数据库字段对应

如果使用Lambda方式，可以更安全地避免字段名写错：

QueryWrapper<SysUser> queryWrapper = new QueryWrapper<>();
queryWrapper.eq(SysUser::getDelFlag, "0")
            .and(wrapper -> wrapper.like(SysUser::getUserName, "粥")
                                 .or()
                                 .like(SysUser::getNickName, "粥"))
            .in(SysUser::getUserId, Arrays.asList(1892512443619762178L, 1892565898380111873L))
            .ne(SysUser::getUserId, 1)
            .eq(SysUser::getTenantId, "000000");