信息表a
letterid letteruid lettertxt letterGroupid
分类表b
letterGroupid letterGroupuid letterGroupname
2个表里面的letterGroupid是相同的,表示分类的id现在的查询语句是这样的:SELECT * FROM a WHERE (Letteruid ='" + uid + "' and LetterGroupid = '" + classid + "') or LetterGroupid = 0 ORDER BY Letterid DESC这样查询出来的结果里面没有 b 表中的letterGroupname这一列,我想利用2个表里面的 letterGroupid把分类名称这一列加入到查询结果中,请大家帮帮忙,谢谢!
letterid letteruid lettertxt letterGroupid
分类表b
letterGroupid letterGroupuid letterGroupname
2个表里面的letterGroupid是相同的,表示分类的id现在的查询语句是这样的:SELECT * FROM a WHERE (Letteruid ='" + uid + "' and LetterGroupid = '" + classid + "') or LetterGroupid = 0 ORDER BY Letterid DESC这样查询出来的结果里面没有 b 表中的letterGroupname这一列,我想利用2个表里面的 letterGroupid把分类名称这一列加入到查询结果中,请大家帮帮忙,谢谢!
WHERE a.letterGroupid = b.letterGroupid
and ((a.Letteruid ='" + uid + "' and a.LetterGroupid = '" + classid + "')
or a.LetterGroupid = 0) ORDER BY a.Letterid DESC
left join b n1 on m.letteruid = n1.letteruid
left join b n2 on m.letterGroupid = n2.letterGroupuid自己再加上其他条件或限制.