邮件使用情况统计方法如下: ) AS domain, COUNT(DISTINCT [column_name]) AS mail_count, COUNT([column_name]) AS mail_sum, AS percent FROM [table_name] WHERE [column_name] LIKE '%@%' GROUP BY domain DISTINCT用来排除重复的邮箱地址,domain是邮箱域名,mail_count是统计某域名下不重复的邮箱地址数量,mail_sum…