Springboot integrates MyBatis-plus: single data query, batch query, conditional query, paging query

Springboot integrates MyBatis-plus: single data query, batch query, paging query

One, single data query

//单条数据查询
    @Test
    public void testSelectById(){
   
    
    
        Stu_info user = stuMapper.selectById(2);
        System.out.prin