LeetCode（数据库）- 部门工资最高的员工

Posted 2021-05-19 Lux_Sun

题目链接：点击打开链接

 

题目大意：略。

 

解题思路：解决方案(1) 和 解决方案(2) 思路都是差不多的：先子查询查出每个部门的最高薪资，然后做下表关联拼接即可~区别无非在于子查询的关联上，前者用的是笛卡尔积，后者用的是 IN 语法（没想到 IN 还可以多个值同时去对齐吧）

 

AC 代码

-- 解决方案(1)
SELECT d.Name Department, e.Name Employee, e.Salary
FROM Employee e
JOIN Department d
ON e.DepartmentId = d.Id,
(SELECT MAX(Salary) Salary, DepartmentId
FROM Employee 
GROUP BY DepartmentId) rs
WHERE rs.Salary = e.Salary AND rs.DepartmentId = e.DepartmentId

-- 解决方案(2)
SELECT
    Department.name AS 'Department',
    Employee.name AS 'Employee',
    Salary
FROM
    Employee
        JOIN
    Department ON Employee.DepartmentId = Department.Id
WHERE
    (Employee.DepartmentId , Salary) IN
    (   SELECT
            DepartmentId, MAX(Salary)
        FROM
            Employee
        GROUP BY DepartmentId
	)
;