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原创 老杜mysql 34题

7、求平均薪水的等级最低的部门的部门名称mysql> select d.dname,h.* from dept d join (select s.grade,t.* from salgrade s join (select avg (sal) as avg, deptno from emp group by deptno) t on t.avg > s.losal and t.avg < s.hisal) h on d.deptno = h.deptno -> where