COUNT（*）返回多行而不是只返回一行

问题描述

为什么COUNT（）返回多行，当我只需要我查询生成多少行的总数？

返回1078。

>

COUNT（）正常工作。 当组通过子句时， count（）给出 GROUP BY 。如果您希望获取包含 group by 的查询中的行数，请改用它作为子查询。

像：

  SELECT COUNT（*）FROM（SELECT * FROM`table` 
 GROUP BY`column1 `）AS`a` 
  

Why does COUNT() return multiple rows when I just need the total count of how many rows my query generates?

Should return 1078.

解决方案

The COUNT() is working as expected. When you put a group by clause, the count() gives you the result for GROUP BY. If you wish to get the count of rows in a query that includes group by, use it as a subquery instead.

Something like:

SELECT COUNT(*) FROM (SELECT * FROM `table`
                      GROUP BY `column1`) AS `a`

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