LeetCode / Reformat Department Table

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

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문제 

+-------------+---------+

| Column Name | Type    |

+-------------+---------+

| id          | int     |

| revenue     | int     |

| month       | varchar |

+-------------+---------+

In SQL,(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"].

 

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.

The result format is in the following example.

 

 

내풀이

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

 

데이터리안 sql실전반에서 추천해준 연습문제 ㅇㄴㅇ