查找重复的电子邮件地址

Question

我需要在我们的数据库中找到重复的电子邮件。我正在一张桌子上查看这些信息。到目前为止我有什么

 SELECT name.email, name.ID

 From Name
 Group BY Name.ID, Name.EMAIL
 Having Count(*) > 1

我知道这是错误的，但不确定如何恰当地写它。

Answer 1

删除ID

 SELECT name.email
 From   Name
 Group  BY Name.EMAIL
 Having Count(*) > 1

如果你想获得电子邮件的数量，

 SELECT name.email, COUNT(*) totalEmailCount
 From   Name
 Group  BY Name.EMAIL
 Having Count(*) > 1

Answer 2

查询将是

SELECT name.email, COUNT(*) FROM Name 
GROUP BY Name.email HAVING COUNT(*) > 1

您需要知道的是，如果您按ID分组，则计数将为1，这就是您的查询无效的原因。

如果您需要知道电子邮件重复的用户的ID，您可以这样做：

select Name.ID, Name.Email from Name where Name.Email in (

SELECT name.email FROM Name 
    GROUP BY Name.email HAVING COUNT(*) > 1
)

Answer 3

下面的SQL查询将返回包含相同（重复）EMAIL的第一条匹配行的ID和EMAIL

select ID, EMAIL from Name group by EMAIL having count(EMAIL) > 1

如果有人要从“名称”表中获取所有重复的EMAIL，则他/她可以执行以下SQL查询

select EMAIL from Name group by EMAIL having count(EMAIL) > 1

请注意：SQL是一种完全不区分大小写的语言。

Answer 4

你走了：

SELECT name.email, COUNT(*)
FROM
    Name
GROUP BY
    Name.email
HAVING 
    COUNT(*) > 1

Answer 5

 select id,email from 
 (select id,email,count(email) over (partion by email order by id) cnt from name) where cnt>1