mysql – SQL计算值在多列中出现的次数？

我在mysql数据库中有两列,我想计算单个名称出现在两列中的次数. COUNT函数本身对我不起作用,因为它只计算一列中的总数.

MySql列：

+-----------------+--------------+
| Member1         | Member2      |
+-----------------+--------------+
| John            | Bill         | 
| Bill            | John         |
| Joe             | John         |
| Bill            | Joe          |
| John            | Steve        |
+-----------------+--------------+

期望的输出：

+-----------------+--------------+
| Member          |     Total    |
+-----------------+--------------+
| John            | 4            | 
| Bill            | 3            |
| Joe             | 2            |
| Steve           | 1            |
+-----------------+--------------+

有任何想法吗？？谢谢！

最佳答案

您可以使用以下内容将使用UNION ALL将多列成员拆分为单个列.一旦它在单列中,那么您可以应用聚合函数计数：

select member,count(*) Total
from 
(
  select member1 as member
  from yt
  union all
  select member2
  from yt
) d
group by member
order by total desc;

见SQL Fiddle with Demo

原文地址：https://www.jb51.cc/mysql/433454.html