sql notes: hackerrank top earners

Problem

We define an employee’s total earnings to be their monthly salary x months worked, and the maximum total earnings to be the maximum total earnings for any employee in the Employee table. Write a query to find the maximum total earnings for all employees as well as the total number of employees who have maximum total earnings. Then print these values as space-separated integers.

Input Format
The Employee table containing employee data for a company is described as follows:

where employee_id is an employee’s ID number, name is their name, months is the total number of months they’ve been working for the company, and salary is the their monthly salary.

Sample Input

Sample Output

69952 1

Explanation
The table and earnings data is depicted in the following diagram:

The maximum earnings value is 69952. The only employee with earnings = 69952 is Kimberly, so we print the maximum earnings value (69952) and a count of the number of employees who have earned $69952 (which is 1) as two space-separated values.

Analysis

For this problem, we can compute earnings first, then group data by earnings and get earnings and number of employees for each group. Finally sort groups by earnings in descending order and output the first one.

• compute earnings ==> SELECT (months*salary) as earnings
• output number of employees ==> COUNT(*)
• in Employee table ==> FROM Employee
• group employees by earnings ==> GROUP BY earnings
• sort by earnings in descending order ==> ORDER BY earnings DESC
• output the one having the maximum earnings ==> LIMIT 1

Solution

1

SELECT (months*salary) as earnings, COUNT(*) FROM Employee GROUP BY earnings ORDER BY earnings DESC LIMIT 1;

Link

Top Earners
(中文版) SQL 笔记: Hackerrank Top Earners