[LeetCode-SQL 50] 1907. Count Salary Categories

 

문제

https://leetcode.com/problems/count-salary-categories/?envType=study-plan-v2&envId=top-sql-50

설명

처음에는 UNION ALL을 이용해서 income 컬럼을 기준으로 각 카테고리별로 count 는 구했지만 카테고리 컬럼을 추가하지 못했다.

컬럼을 추가하려면, SELECT "value" AS 컬럼명 을 하면 된다!

=> 행을 추가할 땐, UNION ALL, 열을 추가할 땐 SELECT 을 이용하자.

구현

# Write your MySQL query statement below
( SELECT 'Low Salary' AS category, count(*) AS accounts_count
FROM Accounts a 
WHERE a.income < 20000 )

UNION ALL

( SELECT 'Average Salary' AS category, count(*) AS accounts_count
FROM Accounts a
WHERE a.income >= 20000 AND a.income <=50000 )

UNION ALL

( SELECT 'High Salary' AS category, count(*) AS accounts_count
FROM Accounts a
WHERE a.income > 50000 )