[LeetCode] 1179. Reformat Department Table

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■ 문제

https://leetcode.com/problems/reformat-department-table/

Reformat Department Table - LeetCode

 

Table: Department

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| revenue     | int     |
| month       | varchar |
+-------------+---------+
(id, month) is the primary key of this table.
The table has information about the revenue of each department per month.
The month has values in ["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"].

 

Write an SQL query to reformat the table such that there is a department id column and a revenue column for each month.

Return the result table in any order.

 

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■ 풀이

SELECT id,
       SUM(CASE WHEN month = 'Jan' Then Revenue END) Jan_Revenue,
       SUM(CASE WHEN month = 'Feb' Then Revenue END) Feb_Revenue,
       SUM(CASE WHEN month = 'Mar' Then Revenue END) Mar_Revenue,       
       SUM(CASE WHEN month = 'Apr' Then Revenue END) Apr_Revenue,
       SUM(CASE WHEN month = 'May' Then Revenue END) May_Revenue,
       SUM(CASE WHEN month = 'Jun' Then Revenue END) Jun_Revenue,
       SUM(CASE WHEN month = 'Jul' Then Revenue END) Jul_Revenue,
       SUM(CASE WHEN month = 'Aug' Then Revenue END) Aug_Revenue,
       SUM(CASE WHEN month = 'Sep' Then Revenue END) Sep_Revenue,      
       SUM(CASE WHEN month = 'Oct' Then Revenue END) Oct_Revenue,       
       SUM(CASE WHEN month = 'Nov' Then Revenue END) Nov_Revenue,
       SUM(CASE WHEN month = 'Dec' Then Revenue END) Dec_Revenue
       
       FROM Department
 GROUP BY id;

id 컬럼으로 그룹핑해서 id 별로 month별 revnue를 컬럼으로 피봇해준다.