mybatisplus常用函数

MyBatis-Plus 是 MyBatis 的增强工具库，提供了许多实用的函数。下面是一些常用的函数：

1. eq：等于

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.eq("name", "张三");

2. ne：不等于

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.ne("age", 18);

3. gt：大于

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.gt("age", 18);

4. ge：大于等于

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.ge("age", 18);

5. lt：小于

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.lt("age", 18);

6. le：小于等于

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.le("age", 18);

7. like：模糊查询

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.like("name", "张");

8. notLike：不匹配查询

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.notLike("name", "张");

9. in：包含查询

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.in("age", 18, 20, 22);

10. notIn：不包含查询

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.notIn("age", 18, 20, 22);

11. orderBy：排序

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.orderByAsc("age");

12. select：查询指定列

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.select("id", "name");

13. last：拼接 SQL 语句

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.last("limit 1");

14. exists：子查询

QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.exists("select 1 from user_role where user_id=user.id and role_id=1");