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leetcode-problemset/leetcode/problem/reformat-department-table.html

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<p>Table: <code>Department</code></p>
<pre>
+-------------+---------+
| 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 [&quot;Jan&quot;,&quot;Feb&quot;,&quot;Mar&quot;,&quot;Apr&quot;,&quot;May&quot;,&quot;Jun&quot;,&quot;Jul&quot;,&quot;Aug&quot;,&quot;Sep&quot;,&quot;Oct&quot;,&quot;Nov&quot;,&quot;Dec&quot;].
</pre>
<p>&nbsp;</p>
<p>Reformat the table such that there is a department id column and a revenue column <strong>for each month</strong>.</p>
<p>Return the result table in <strong>any order</strong>.</p>
<p>The result format is in the following example.</p>
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre>
<strong>Input:</strong>
Department table:
+------+---------+-------+
| id | revenue | month |
+------+---------+-------+
| 1 | 8000 | Jan |
| 2 | 9000 | Jan |
| 3 | 10000 | Feb |
| 1 | 7000 | Feb |
| 1 | 6000 | Mar |
+------+---------+-------+
<strong>Output:</strong>
+------+-------------+-------------+-------------+-----+-------------+
| id | Jan_Revenue | Feb_Revenue | Mar_Revenue | ... | Dec_Revenue |
+------+-------------+-------------+-------------+-----+-------------+
| 1 | 8000 | 7000 | 6000 | ... | null |
| 2 | 9000 | null | null | ... | null |
| 3 | null | 10000 | null | ... | null |
+------+-------------+-------------+-------------+-----+-------------+
<strong>Explanation:</strong> 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).
</pre>