通过条件构造器可以实现一些复杂sql实现的功能

• 查询name不为空的用户，并且邮箱不为空的用户，年龄大于等于12

 	@Test
    void conditionSelect(){
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.isNotNull("name")
                .isNotNull("email")
                .ge("age",12);
        userMapper.selectList(wrapper).forEach(System.out::println);
    }

• 查询名字yangqian

	@Test
    void conditionSelect1(){
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.eq("name","yangqian");
        userMapper.selectList(wrapper).forEach(System.out::println);
    }

• 查询年龄在 20 ~ 30 岁之间的用户

	@Test
    void conditionSelect2(){
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.between("age",20,30);
        userMapper.selectList(wrapper).forEach(System.out::println);
    }

• 模糊查询
  • notLike
  • notLike(R column, Object val)
  • notLike(boolean condition, R column, Object val)

	@Test
    void conditionSelect3(){
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.notLike("name","t")
                .likeRight("email","0314");
        userMapper.selectList(wrapper).forEach(System.out::println);
    }

• id在子循环中查询

	@Test
    void conditionSelect5(){
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.orderByAsc("id");
        userMapper.selectList(wrapper).forEach(System.out::println);
    }
    @Test
    void conditionSelect5(){
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.orderByDesc("id");
        userMapper.selectList(wrapper).forEach(System.out::println);
    }