oracle简单查询问题根据emp表中的ENAME字段统计各个部门的员工人数

select a.DEPTNO,b.DNAME,count(a.EMPNO)
from emp a
full join dept b --一定要用full join,inner join会去掉没有部门的人
on b.DEPTNO=a.DEPTNO
group by DEPTNO
order by 2 desc

select count(e.ename),d.dname from emp e right join dept d on e.deptno=d.deptno group by d.dname order by d.dname desc
用一个外连接就可以搞定