如果註冊的用戶數達到一定程度，我們可以在數據庫查詢語句對其進行統計。
以下SQL語句能夠統計出帶某種類型後綴的email郵件註冊量最大，及其排行順序。
SELECT suffix_email, COUNT(suffix_email) AS email_count
FROM (SELECT SUBSTRING(email, CHARINDEX('@', email), 100) AS suffix_email
FROM user_table) temp_table
FROM (SELECT SUBSTRING(email, CHARINDEX('@', email), 100) AS suffix_email
FROM user_table) temp_table
GROUP BY suffix_email
HAVING (COUNT(suffix_email) > 5)
ORDER BY email_count DESC
HAVING (COUNT(suffix_email) > 5)
ORDER BY email_count DESC
某網站對此排名後，發現排名前15的郵箱如下：
@163.com
@126.com
@sina.com
@yahoo.com.cn
@sohu.com
@hotmail.com
@tom.com
@21cn.com
@263.com
@vip.sina.com
@yahoo.com
@163.net
@qq.com
@gmail.com
@eyou.com
