摘要：
部门：dept(deptno,dname)员工：emp(ename,sal,deptno)薪资等级：salgrade(grade,losal,hisal)平均工资的最小值及部门编号和工资等级及部门名称：select t1.deptno,t1.avg_sal,grade,d.dname from ( select deptno,avg_sal,grade from (select deptno,avg(sal) avg_sal from emp group by deptno) t join salgrade s on (t.avg_sal between s.losal and s.hisa. 阅读全文