题目:
编写一个 SQL 查询,找出每个部门工资最高的员工。对于下面的表,您的 SQL 查询应返回以下行(行的顺序无关紧要)。
解题思路:
(1)先对 DepartmentId 字段分组查询最大值,得到不同 DepartmentId 下的最大值
select max(Salary),DepartmentId
from Employee
group by DepartmentId
(2)再用DepartmentId 字段连接 Department 表,根据 Salary 和 DepartmentId 查找 Department.Name 字段
select
d.Name as Department,
e.Name as Employee,
e.Salary
from
Employee e,Department d
where
e.DepartmentId=d.id
and
(e.Salary,e.DepartmentId) in (select max(Salary),DepartmentId from Employee group by DepartmentId);