mysql - 出现次数的总和

Question

我有以下查询:

SELECT num1
    -> from table4
    -> WHERE suffix IN ('mt', 'dn')
    -> GROUP BY num1
    -> HAVING COUNT(DISTINCT suffix) = 2;

这向我展示了以下内容:

1563866656871111 
1563866656876839 
1563866656878888 
1563867854324841

如何才能只得到数字 4？

感谢您的帮助:)

Answer 1

您可以包装现有的查询:

SELECT COUNT(*)
FROM (
    SELECT num1
    FROM table4
    WHERE suffix IN ('mt', 'dn')
    GROUP BY num1
    HAVING COUNT(DISTINCT suffix) = 2
) x

注意:给定您的示例数据，这将返回 3，而不是 4。