sql - 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。我正在一张桌子上寻找这些信息。到目前为止我所拥有的

 SELECT name.email, name.ID

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

我知道这是错误的，但不确定如何正确编写。

Answer 1

去除ID

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

如果您想获取电子邮件的数量，

 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，如果您还按 ID 分组，计数将为 1，这就是您的查询不起作用的原因。

如果您需要知道重复电子邮件的用户的 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 的第一个匹配行的 ID 和 EMAIL

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

如果有人想要 Name 表中所有重复的 EMAIL，那么他/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

干得好：

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

Answer 6

About all posted answers here, using Group by methods. This query can also be written with self join method.

select distinct f.email
from Name f
join Name s
where f.id <> s.id and f.email = s.email

Answer 7

无需将 tableName 放在选择列中

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