我有一个查询,我知道它至少应该返回一行。我如何修改我的关注查询以确保相册返回数据。感谢您的帮助。
在这里查询。我知道相册有一行,我需要将其归还。
select distinct p.*,
a.ID as parentalbumid,a.CreatorID as albumcreatorid,a.AlbumName,a.AlbumDescription,a.AlbumDefaultImageURL,a.Private,a.DateCreated,a.AdultContent,a.PasswordProtected,a.AllowTags,a.TypeID,a.AlbumAutoID,
mainuser.Username as mainuserusername,mainuser.ID as mainuserid,mainuser.PictureUrl as mainuserpictureurl,
c.ID as commentID,c.PhotoID as commentphotoid,c.OutputMessage,c.CommentDate,
t.ID as tagID,t.PhotoID as tagphotoid,t.UserID,t.TextTag,t.LeftLocation,t.TopLocation,
u.ID as userid,u.Username,u.FirstName,u.LastName,u.PictureUrl
from photos p
inner join albums a on a.ID = p.AlbumID
inner join users mainuser on mainuser.ID = p.UserID
left join comments c on c.PhotoID = p.ID
left join tags t on t.PhotoID = p.ID
left join users u on u.ID = c.CommentBy
where a.AlbumAutoID = 3
order by p.DateUploaded desc;
最佳答案
仅使用LEFT JOIN
(并将表albums
作为FROM
的第一个表):
select distinct p.*,
a.ID as parentalbumid,a.CreatorID as albumcreatorid,a.AlbumName,a.AlbumDescription,a.AlbumDefaultImageURL,a.Private,a.DateCreated,a.AdultContent,a.PasswordProtected,a.AllowTags,a.TypeID,a.AlbumAutoID,
mainuser.Username as mainuserusername,mainuser.ID as mainuserid,mainuser.PictureUrl as mainuserpictureurl,
c.ID as commentID,c.PhotoID as commentphotoid,c.OutputMessage,c.CommentDate,
t.ID as tagID,t.PhotoID as tagphotoid,t.UserID,t.TextTag,t.LeftLocation,t.TopLocation,
u.ID as userid,u.Username,u.FirstName,u.LastName,u.PictureUrl
from albums a
left join photos p on a.ID = p.AlbumID
left join users mainuser on mainuser.ID = p.UserID
left join comments c on c.PhotoID = p.ID
left join tags t on t.PhotoID = p.ID
left join users u on u.ID = c.CommentBy
where a.AlbumAutoID = 3
order by p.DateUploaded desc;
关于Mysql查询帮助。我需要确保至少返回一条记录,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9846272/