mysql - SQL 查询以查找具有相同电子邮件域的最大计数

Question

我有一个电子邮件 ID 列，用于存储完整的电子邮件 ID。 我想根据域获得最大计数，即@gmail.com，@xyz.com 似乎在 GROUP BY 子句中我们不能应用任何通配符，它​​只会考虑来自完整电子邮件地址的域。

Answer 1

对于Mysql

SELECT SUBSTRING_INDEX(EMail.EMail, '@', -1) AS `Email Domain`, COUNT(*)
FROM EMail
GROUP BY SUBSTRING_INDEX(EMail.EMail, '@', -1)

以数据为例

SELECT SUBSTRING_INDEX(EMail.EMail, '@', -1) AS `Email Domain`, COUNT(*)
FROM
  (
  select 'tuhin@gmail.com' as EMail
  UNION
    SELECT 'tuhin@yahoo.com'
    union
    select 'abc@xyz.com'
    union
      select 'hin@gmail.com'
  ) as EMail

  GROUP BY SUBSTRING_INDEX(EMail.EMail, '@', -1)

对于 SQL 服务器

SELECT RIGHT(Email, LEN(Email) - CHARINDEX('@', email)) Domain ,
COUNT(Email) EmailCount
FROM   dbo.email
WHERE  LEN(Email) > 0
GROUP BY RIGHT(Email, LEN(Email) - CHARINDEX('@', email))
ORDER BY EmailCount DESC