MySQL:枢轴+计数 [英] MySQL: Pivot + Counting

问题描述

我需要有关将转换此表的SQL的帮助:

I need help with a SQL that will convert this table:

===================
| Id | FK | Status|
===================
| 1  | A  | 100   |
| 2  | A  | 101   |
| 3  | B  | 100   |
| 4  | B  | 101   |
| 5  | C  | 100   |
| 6  | C  | 101   |
| 7  | A  | 102   |
| 8  | A  | 102   |
| 9  | B  | 102   |
| 10 | B  | 102   |
===================

对此:

==========================================
| FK | Count 100 | Count 101 | Count 102 |
==========================================
| A  | 1         | 1         | 2         |
| B  | 1         | 1         | 2         |
| C  | 1         | 1         | 0         |
==========================================

我可以这么简单地进行计数等，但是在尝试用导出的信息来旋转表方面却很费劲.感谢您的帮助.

I can so simple counts, etc., but am struggling trying to pivot the table with the information derived. Any help is appreciated.

推荐答案

使用:

  SELECT t.fk,
         SUM(CASE WHEN t.status = 100 THEN 1 ELSE 0 END) AS count_100,
         SUM(CASE WHEN t.status = 101 THEN 1 ELSE 0 END) AS count_101,
         SUM(CASE WHEN t.status = 102 THEN 1 ELSE 0 END) AS count_102
    FROM TABLE t
GROUP BY t.fk

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