匹配字段数（列）

Question

出于好奇，有没有办法可以获得2个或更多表中匹配数据的数量..如果我们得到以下3个表，

tbl_1-
ip  |isp    |infection
----------------------
1   |aaaa   |malware
2   |bbbb   |malware
3   |cccc   |ddos
3   |cccc   |trojan
4   |dddd   |ddos

tbl_2-
ip  |isp    |infection
----------------------
1   |aaaa   |malware
3   |cccc   |ddos
4   |dddd   |trojan
5   |eeee   |trojan
6   |ffff   |other

tbl_3-
ip  |isp    |infection
----------------------
1   |aaaa   |ddos
6   |ffff   |
2   |bbbb   |other

我能否得到如下所示的答案？

Result-
ip  |isp    |infection  |Match Count
------------------------------------
1   |aaaa   |malware    |2      
1   |aaaa   |ddos       |1      
2   |bbbb   |malware    |1
2   |bbbb   |other      |1
3   |cccc   |ddos       |2
3   |cccc   |trojan     |1
4   |dddd   |ddos       |1
4   |dddd   |trojan     |1
5   |eeee   |trojan     |1
6   |ffff   |other      |1
6   |ffff   |           |1

谢谢：）

Answer 1

您需要使用UNION ALL（ 不仅仅是UNION ）才能允许重复

SELECT ip, isp, infection, COUNT(*)
FROM 
(
SELECT ip, isp, infection FROM tbl_1
UNION ALL
SELECT ip, isp, infection FROM tbl_2
UNION ALL
SELECT  ip, isp, infection FROM tbl_3
) x
GROUP BY ip, isp, infection

SQLFiddle Demo

Answer 2

您应该执行所有三个表中的UNION ALL，然后通过ip，isp，感染列运行GROUP BY。

SELECT ip, isp, infection, COUNT(*) 'Match Count'
FROM
(
    SELECT * FROM tbl_1
    UNION ALL
    SELECT * FROM tbl_2
    UNION ALL
    SELECT * FROM tbl_3
) AS A
GROUP BY ip, isp, infection

Answer 3

是的，您可以使用COUNT（）函数 http://dev.mysql.com/doc/refman/5.1/en/group-by-functions.html#function_count