[英]Selecting rows with multiple values for a column
在MySQL上,给定下表(image_tags):
image_id | tag_id
-----------------
1 | 100
1 | 20
2 | 100
3 | 20
我想选择tag_id = 100 AND tag_id = 20的行,在这种情况下,我想要的结果是:
image_id
--------
1
我尝试过,但是找不到在纯SQL中执行此操作的正确方法。 谢谢!
假设( image_id
, tag_id
)对是唯一的:
SELECT image_id
FROM image_tags
WHERE tag_id IN ('20', '100')
GROUP BY image_id
HAVING count(*) = 2
试试这个:
SELECT image_id FROM MyTable
WHERE tag_id IN (100,20)
GROUP BY image_id
HAVING COUNT(*) = 2
如果要选择每一行,请尝试以下操作:
SELECT * FROM MyTable
WHERE image_id IN
(
SELECT image_id FROM MyTable
WHERE tag_id IN (100,20)
GROUP BY image_id
HAVING COUNT(*) = 2
)
简单的JOIN查询
SELECT a.image
FROM image_tags a
INNER JOIN image_tags b ON a.image_id = b.image_id AND b.tag_id = 20
WHERE a.tag_id = 100
或使用计数,但应对图像是否存在重复标签
SELECT DISTINCT image_id
FROM image_tags
WHERE tag_id in ('20', '100')
GROUP BY image_id
HAVING count(DISTINCT tag_id) = 2
您所做的是对的,您也可以尝试一下
从image_tags中选择*,其中tag_id位于('100','20',....)
SELECT Image_ID FROM
(SELECT Image_ID FROM tab
WHERE Tag_ID = 100) tag100
JOIN
(SELECT Image_Id FROM tab
WHERE TagID = 20) tag20
我认为这就是您要寻找的-您想要同时具有TagID等于20和TagID等于100的那些记录,对吗?
select image_id
from image_tags
where image_id IN (
select image_id
from image_tags
where tag_id = 100)
AND tag_id = 20
您可以使用
select image_id from test
where image_id IN (select image_id from test
where tag_id = '100') AND tag_id = '20'
检查演示
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