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我有一个查询,左连接的一部分要么返回数据或空。但即使有现有记录,它也不会返回任何数据。左连接部分的扭曲是我只想检索一条记录(如果存在)。谢谢你的帮助。MySQL查询不recieving我左边的任何数据连接
select a.*,p.thumbnailphotopath as AlbumPicture
from (select * from album_access) ac
inner join (select * from albums) a on a.ID = ac.AlbumID
left join (
select * from photos
where IsProcessed = 1 order by DateUploaded desc limit 1
) p
on a.ID = p.AlbumID #should return one if exist.
where ac.AccessUserID = '35e44a8e-643a-4c4f-8a46-59911a1e7c53'
and ac.FullControl = 1 and a.Private = 1
谢谢这个工作,我不明白你是如何得到它返回只有一个值?是MAx关键字? – user516883 2012-04-19 18:58:36
再次感谢您的帮助 – user516883 2012-04-19 19:13:49