LeetCode-in-Java
1179. Reformat Department Table
Easy
SQL Schema
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.
The query result format is in the following example.
Example 1:
Input:
Department table:
+------+---------+-------+
| id | revenue | month |
+------+---------+-------+
| 1 | 8000 | Jan |
| 2 | 9000 | Jan |
| 3 | 10000 | Feb |
| 1 | 7000 | Feb |
| 1 | 6000 | Mar |
+------+---------+-------+
Output:
+------+-------------+-------------+-------------+-----+-------------+
| id | Jan_Revenue | Feb_Revenue | Mar_Revenue | ... | Dec_Revenue |
+------+-------------+-------------+-------------+-----+-------------+
| 1 | 8000 | 7000 | 6000 | ... | null |
| 2 | 9000 | null | null | ... | null |
| 3 | null | 10000 | null | ... | null |
+------+-------------+-------------+-------------+-----+-------------+
Explanation: The revenue from Apr to Dec is null.
Note that the result table has 13 columns (1 for the department id + 12 for the months).
Solution
# Write your MySQL query statement below
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