order by 关键字（升降）

--order by 关键字

--作用：用于对查询结果进行排序

 

select * from emp where deptno = 20 order by sal

 

--1.如何决定升序还是降序？

select * from emp where deptno = 20 order by sal asc

select * from emp where deptno = 20 order by sal desc

--2.如果排序的列相同时，如何处理

select * from emp where deptno =20 order by sal desc,ename

select * from emp where deptno =20 order by sal desc,ename desc