SQL，在多列中计数然后分组 [英] SQL, count in multiple columns then group by

问题描述

我试图在多列中计数，然后按总和分组，其中任何列中出现相同的数据

I am trying to count in multiple columns then group by for a total sum where the same data appears in any column

Source data table:

P1  P2  P3
-----------
a   b   
a   a   a
b   c   
a   b   b
b   a

我希望它显示如下内容:

I want it to show something like this:

Desired query output:

     Total
   -------------
a |    6
b |    5
c |    1

推荐答案

可以使用联合查询

SELECT x.f1,Count(x.f1) FROM
(SELECT p1 As F1 FROM table
 UNION ALL
 SELECT p2 As F1 FROM table
 UNION ALL
 SELECT p3 As F1 FROM table) x
GROUP BY x.f1

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