字段列表中的“大小”列不明确

Question

无效的SQL：

SELECT
 info_hash,
 size,
 comment,
 created_by,
 announce_list,
 completed_by, 
 completed,
 seeders,
 leechers,
 ulspeed,
 dlspeed,
 dateline,
 thumbnail_dateline, 
 filename,
 filesize,
 visible,
 attachmentid,
 counter,
 postid, 
 IF(thumbnail_filesize > 0, 1, 0) AS hasthumbnail,
 thumbnail_filesize,
 attachmenttype.thumbnail AS build_thumbnail,
 attachmenttype.newwindow
FROM attachment
LEFT JOIN attachmenttype AS attachmenttype USING (extension)
WHERE postid IN (-1,2)
ORDER BY attachmentid;

MySQL错误：字段列表中的列“大小”不明确，错误编号：1052

Answer 1

这意味着attachment和attachmenttype都可能是size 。

如果您限定列名，那么您将永远不会遇到此类问题。

Answer 2

@GordonLinoff有正确的答案。 但是，如果您只是从某个地方复制了此代码，那么您将很难理解他在说什么。 （也很好地问是更好的）。

以此为基础。 注意如何将A.添加到size如果任何字段再次不正确，则必须向其中添加A.或T. .。

SELECT info_hash, 
 A.size,
 comment,
 created_by,
 announce_list,
 completed_by, 
 completed, 
 seeders, 
 leechers, 
 ulspeed, 
 dlspeed,
 dateline, 
 thumbnail_dateline, 
 filename, 
 filesize, 
 visible,
 attachmentid, 
 counter,
 postid,
 IF(thumbnail_filesize > 0, 1, 0) AS hasthumbnail,
 thumbnail_filesize,
 T.thumbnail AS build_thumbnail, 
 T.newwindow
FROM attachment A
LEFT JOIN attachmenttype AS T USING (extension)
WHERE A.postid IN (-1,2)
ORDER BY A.attachmentid;