具有重复电子邮件 ID 的不同行数

Posted 2023-02-24

【中文标题】具有重复电子邮件 ID 的不同行数

【英文标题】：Count of distinct rows with duplicate email IDs

【发布时间】：2011-03-19 02:29:22

【问题描述】：

如何在 SQL 中获取具有重复电子邮件 ID 的不同行的计数？

ID   NAME   EMAIL 
1    John   [e-mail] 
2    Sam    [e-mail] 
4    Bob    [e-mail] 
5    Tom    [e-mail] 
6    Rob    [e-mail]
7    Tic    [e-mail]
8    Dad    [e-mail]

查询应该返回 2。 [e-mail] 和 [e-mail] 是重复的

SELECT 
 COUNT(*)  
FROM Users
GROUP BY EMail 
HAVING ( COUNT(EMAIL) > 1 )    

这个查询返回了一些奇怪的结果。 谢谢

【参考方案1】：

行数：

select sum(cnt)
from (select count(*) as cnt
    from Users
    group by email
    having count(*) > 1) T

电子邮件数量：

select count(*)
from (select count(*) as cnt
    from Users
    group by email
    having count(*) > 1) T

两者兼而有之：

select count(*) as COUNT_EMAIL sum(cnt) as COUNT_ROWS
from (select count(*) as cnt
    from Users
    group by email
    having count(*) > 1) T

以上应该适用于 SQL Server 和 Oracle。