企业部门表员工表建表sql带数据;mysql练手sql语句集合,带讲义;
计算员工的年薪;列出员工的编号,姓名和年薪
> select empno, ename, sal*12 as yearsal
> from emp;
计算部门平均薪水;列出部门编号,部门名和平均薪水
```sql
select t.deptno,dept.dname, t.avgsal
from (select deptno, avg(sal) as avgsal
from emp
group by deptno) as t
join dept
on dept.deptno = t.deptno;
```