題目摘要
選出每棟Department中薪水最高的人(每棟樓不知一個)
解法
Solution1
# Write your MySQL query statement below
SELECT d.Name AS Department, e.Name As Employee, e.Salary
From Employee AS e
INNER JOIN (
SELECT max(Salary) AS Salary, DepartmentId
FROM Employee
GROUP BY DepartmentId
) AS et
ON e.Salary = et.Salary AND e.DepartmentId = et.DepartmentId
INNER JOIN Department AS d
ON e.DepartmentId = d.Id注意
Solution1
1. 由於不止一個，所以連表的主表不能是GROUP BY出來的字表
可問問題
原題
The Employee table holds all employees. Every employee has an Id, a salary, and there is also a column for the department Id.
+—-+——-+——–+————–+
| Id | Name | Salary | DepartmentId |
+—-+——-+——–+————–+
| 1 | Joe | 70000 | 1 |
| 2 | Henry | 80000 | 2 |
| 3 | Sam | 60000 | 2 |
| 4 | Max | 90000 | 1 |
+—-+——-+——–+————–+
The Department table holds all departments of the company.
+—-+———-+
| Id | Name |
+—-+———-+
| 1 | IT |
| 2 | Sales |
+—-+———-+
Write a SQL query to find employees who have the highest salary in each of the departments. For the above tables, Max has the highest salary in the IT department and Henry has the highest salary in the Sales department.
+————+———-+——–+
| Department | Employee | Salary |
+————+———-+——–+
| IT | Max | 90000 |
| Sales | Henry | 80000 |
+————+———-+——–+