我在数据库中有以下数据
MAILFROM, MAILTO , TIMESTAMP, MESSAGE
A B 2013-07-01 12:11:12, Hi
B A 2013-07-01 12:12:12, Hi back
A B 2013-07-01 12:13:12, How are you
A C 2013-07-01 12:14:12, Hi there
D A 2013-07-01 12:16:12, Hi
C D 2013-07-01 12:17:12, Hi
如何将其与select组合,以便我得到
AC'评论发生3次
SELECT MAILFROM, MAILTO FROM messages WHERE 'A' IN(FROM,TO) GROUP BY FROM
给
AC和CA但我希望组合在一起.
它只显示AC 3次
该示例是一个邮箱.
这包含:
MAILFROM, MAILTO , TIMESTAMP, MESSAGE
A B 2013-07-01 12:11:12, Hi
B A 2013-07-01 12:12:12, Hi back
A B 2013-07-01 12:13:12, How …