184. Department Highest Salary

Description

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	Jim	90000	1
3	Henry	80000	2
4	Sam	60000	2
5	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, your SQL query should return the following rows (order of rows does not matter).

Department	Employee	Salary
IT	Max	90000
IT	Jim	90000
Sales	Henry	80000

Constraints

Approach

Links

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Examples

Example 1

Input:

{"headers": {"Employee": ["Id", "Name", "Salary", "DepartmentId"], "Department": ["Id", "Name"]}, "rows": {"Employee": [[1, "Joe", 70000, 1], [2, "Jim", 90000, 1], [3, "Henry", 80000, 2], [4, "Sam", 60000, 2], [5, "Max", 90000, 1]], "Department": [[1, "IT"], [2, "Sales"]]}}

Output:

{"headers": ["Department", "Employee", "Salary"], "values": [["IT", "Jim", 90000], ["Sales", "Henry", 80000], ["IT", "Max", 90000]]}

Explanation:

Max and Jim both have the highest salary in the IT department and Henry has the highest salary in the Sales department.

Solutions

Solution 1

# MySQL query statement

SELECT dept.Name AS 'Department', emp.Name AS 'Employee', emp.Salary
FROM Employee emp
JOIN Department dept 
ON emp.DepartmentId = dept.Id
WHERE (emp.DepartmentId, Salary) 
IN (SELECT DepartmentId, MAX(Salary) 
    FROM Employee 
    GROUP BY DepartmentId
   );

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