MyBatis-Plus_查询进阶01

select语句中不列出全部字段

文章目录

1. 形式1

/**
     * 1. 名字包含雨并且年齡小于40
     * sql：name like '%雨%' and age < 40
     */
    @Test
    public void selectByWrapperSupper() {
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
//        queryWrapper.like("name", "雨").lt("age", 40);
        queryWrapper.select("id", "name").like("name", "雨").lt("age", 40);

        List<User> userList = userMapper.selectList(queryWrapper);
        userList.forEach(System.out::println);
    }
    /*
      sql形式：SELECT id,name FROM user WHERE name LIKE ? AND age < ?
     这种情况，你查询什么列，如果有值就会查询出来，没查询的列的值默认为null
     */

2. 形式2

  /**
     * 2. 名字包含雨并且年齡小于40
     * sql：name like '%雨%' and age < 40
     */
    @Test
    public void selectByWrapperSupper2() {
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
//        queryWrapper.like("name", "雨").lt("age", 40);
        queryWrapper.like("name", "雨")
                .lt("age", 40)
                .select(User.class, tableFieldInfo -> !tableFieldInfo.getColumn().equals("create_time")
                        && !tableFieldInfo.getColumn().equals("manager_id"));

        List<User> userList = userMapper.selectList(queryWrapper);
        userList.forEach(System.out::println);
    }
    /*
      sql形式：SELECT id,name FROM user WHERE name LIKE ? AND age < ?
     */

​