1. 查询语句

select * from user where id in (5,21,6);

查询结果是不是按照参数顺序排列的，为了保证查询顺序可以使用

select * from sj_user where id in(5,21,6) order by FIELD(id,5,21,6);
//或者
select * from sj_user where id in(5,21,6) order by FIND_IN_SET(id,'5,21,6');