做热饮店网站营销运营主要做什么

025排序操作

select .. from .. order by 字段 asc/desc

select empno, ename, sal from emp order by sal asc;

多个字段排序

查询员工的编号、姓名、薪资，按照薪资升序排列，如果薪资相同的，再按照姓名升序排列。

select empno,ename,sal from emp order by sal asc, ename asc;
select empno,ename,sal from emp order by 3 asc, 2 asc;

select ename,job,sal from emp where job in ('MANAGER','SALESMAN') order by sal desc;

select ename,job,sal*12 as yearsal from emp where job in ('MANAGER','SALESMAN') order by yearsal asc;

说明order在select后执行，优先级低

select ename,job,sal*12 as yearsal from emp where job in ('MANAGER','SALESMAN') order by sal asc;

按原始名字sal排序也可