子查询二(在HAVING子句中使用子查询)

 --查询部门编号，人数，平均工资，并且要求这些部门的平均工资高于公司的平均工资
 SELECT e.deptno,COUNT(e.empno),ROUND(AVG(e.sal),2)
 FROM emp e
 GROUP BY e.deptno
 HAVING AVG(e.sal)>(
        SELECT AVG(sal)
        FROM emp
 );
 

 --查询出部门平均工资高的部门名称和平均工资
SELECT d.deptno,d.dname,AVG(e.sal) avgsal
FROM emp e,dept d
WHERE e.deptno=d.deptno
GROUP BY d.deptno,d.dname
HAVING AVG(e.sal)=(
    SELECT MAX(AVG(sal))
     FROM emp
     GROUP BY deptno
);