Question

我有3个表用于存储图像，标签和两者之间的链接。结构是这样的：

表 - 照片

pid     name
--------------
1       image1
2       image2
3       image3
4       image4

表格 - 标签

tagID   tagName
---------------
1       red
2       blue
3       yellow
4       green

表 - photo_tag_bridge

pid     tagID
-------------
1       1
2       1
3       1
1       2
1       3

我想创建一个SELECT语句，只检索来自＆＃39;照片的行。匹配多个tagID＆＃39; s。我目前已经尝试将image1与tagID 1和2

匹配

SELECT photos.pid
, photo_tag_bridge.pid, photo_tag_bridge.tagID
, tags.tagID 
FROM photos
, photo_tag_bridge
, tags 
where photos.pid = photo_tag_bridge.pid 
AND photo_tag_bridge.tagID = 1 
AND photo_tag_bridge.tagID = 2 
GROUP BY photos.pid

这并没有带回任何东西，似乎我可能需要使用INNER JOIN？

Answer 1

有两个明显的解决方案。一种是加入2个photo_tag_bridge实例（如果您实际使用此表中的任何数据，则加入两个标记实例）：

SELECT photos.pid FROM photos , photo_tag_bridge ptb_a , photo_tag_bridge ptb_b WHERE photos.pid = ptb_a.pid AND photos.pid = ptb_b.pid AND ptb_a.tagID = 1 AND ptb_b.tagID = 2

或者你做一个将DISTINCT计数与所需匹配数匹配的聚合（这很容易匹配，例如，3个标签中的任意两个）：

SELECT photos.pid FROM photos , photo_tag_bridge ptb WHERE photos.pid = ptb_a.pid AND photos.pid = bptb_b.pid AND ptb.tagID IN (1,2) GROUP BY photos.pid HAVING COUNT(DISTINCT ptb.tagID)=2;

Answer 2

至于我的理解，你需要获得具有多个标签的照片ID。

 create table #photo(id int,name varchar(10))
 create table #phototag(pid int,tgid int)
 create table #tag(id int,name varchar(10))

 select p.id,p.name from #photo p inner join #phototag pt on pt.pid=p.id group by p.id,p.name having count(*)>1

Mysql WHERE X匹配Y和Z.

2 个答案: