我需要在两个表中选择外键彼此匹配,但是我不想重复相同的外键。
我在数据库上有这些表:
|照片| (0 / *)---------(1)|广告| |照片| -photo_id -url -advertisement_id |广告| -advertisement_id ...
数据库数据
|照片| photo_id | 网址| advertise_id 1 | x | 1 2 | x | 1 3 | x | 2 4 | x | 3
我要这个:
ID | 网址 1 | x 2 | x->这是任何人的网址 3 | X
我在下面尝试SQL,但是此重复ID =(
选择a.advertisement_id作为ID,选择p.url作为URL 来自广告 正确的连接照片p 在a.advertisement_id = p.advertisement_id LIMIT 6
结果:
ID | 网址 1 | http://i0.statig.com.br/bancodeimagens/18/46/2h/18 ... 2 | http://www.yaves.es/images/Animales/Tiernos-Gatito ... 2 | http://images.forwallpaper.com/files/thumbs/previe ... 10 | http://www.petmag.com.br/img/gatos/racas/7892/euro ... 7 | http://www.gmstatic.com/content/images/1369932859 _... 8 | http://www.navegandonaweb.com/wp-content/uploads/2 ...
有人帮我构造SQL查询吗?
SELECT a.advertisement_id as ID, p.url as URL
FROM Advertisement a
RIGHT JOIN Photo p
ON a.advertisement_id = p.advertisement_id
GROUP BY a.advertisement_id
ORDER BY p.photo_id ASC (or DESC ? )
LIMIT 6
或者
SELECT a.advertisement_id as ID, p.url as URL
FROM Advertisement a,Photo p
WHERE a.advertisement_id = p.advertisement_id
GROUP BY a.advertisement_id
ORDER BY p.photo_id ASC (or DESC ? )
LIMIT 6
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我来说两句