Question

我正在为包含某些媒体文件的压缩文件创建数据库。要连接每个.zip中的文件，我使用中间表compressed_has_medium。

数据库

medium           compressed_has_medium             compressed
id | filename    id | medium_id | compressed_id    id | filename
--------------   ------------------------------    -------------
 1 | file1.mp3    1 |  1        |  1                1 | compressed1.zip
 2 | file2.mp3    1 |  2        |  1                2 | compressed2.zip
 3 | file3.mp3    1 |  3        |  1                3 | compressed3.zip
 4 | file4.mp3    1 |  4        |  1
 5 | file5.mp3    1 |  5        |  1
 6 | file6.mp3    1 |  6        |  1
 7 | file7.mp3    1 |  1        |  2
 8 | file8.mp3    1 |  2        |  2
 9 | file9.mp3    1 |  3        |  2

问题

我需要返回包含我发送给MySQL的ID的每个.zip。如果zip1有文件1,2,3,4,5,6并且我想要文件3,4的zip，它应该返回zip1。但是如果zip2有文件1,2,3并且我请求文件3,4，则不应该返回。

部分解决方案

我已经尝试了很多并且得到了这个解决方案：http://sqlfiddle.com/#!9/cb0864/37但这是一个非常丑陋的查询，可能效率不高。

SELECT c.*, GROUP_CONCAT(cm.medium_id) as media
FROM compressed as c
INNER JOIN compressed_has_medium as cm
ON cm.compressed_id = c.id
GROUP BY cm.compressed_id
HAVING (media LIKE '%,3,%' OR media LIKE '3,%' OR media LIKE '%3')
AND (media LIKE '%,4,%' OR media LIKE '4,%' OR media LIKE '%,4')

你知道更好的方法吗？

许多坦克！

Answer 1

可能这是你所期待的我相信

我已经改变了你的小提琴中的查询：http://sqlfiddle.com/#!9/cb0864/62

SELECT c.*,GROUP_CONCAT(cm.medium_id) as media
FROM compressed as c
LEFT JOIN compressed_has_medium as cm 
ON cm.compressed_id = c.id
WHERE cm.medium_id in (3,4)
GROUP BY cm.compressed_id 
having sum(cm.medium_id in (3,4)) = 2 and   // 2 represents the numbers of medium id you are entering
sum(cm.medium_id not in (3,4)) = 0

MySQL从多个ID获取分组加入

1 个答案: