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Home Backend Development PHP Tutorial 求教关于MYSQL两个表的语句问题

求教关于MYSQL两个表的语句问题

Jun 23, 2016 pm 01:27 PM

$sql = "SELECT a.id,a.cover,a.name,a.name2,b.id,b.likes,b.month FROM dede_aiyunma_user AS a,dede_aiyunma_thing AS b WHERE a.id=b.id order by a.id desc";$dsql->Execute('me',$sql);while($row = $dsql->GetArray('me')){$uid = $row['id'];$cover = $row['cover'];$fname = $row['name'];$mname = $row['name2'];$like = $row['likes'];}
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求教大神们,可以显示a和b表里的数据了,现在要求b.likes字段可以根据b.month字段显示,这个语句该怎么变?
如果后面变成 WHERE a.id=b.id and b.month= $month order by a.id desc ,那么就是两个表的条件,让where b.month= $month只对B表起作用怎么写?


回复讨论(解决方案)

b.month= $month 本来就只对B表起作用

b.month= $month 本来就只对B表起作用


你好,感觉回复
$sql = "SELECT a.id,a.cover,a.name,a.name2,b.id,b.likes,b.month FROM dede_aiyunma_user AS a,dede_aiyunma_thing AS b WHERE a.id=b.id and b.month= $month order by a.id desc";$dsql->Execute('me',$sql);while($row = $dsql->GetArray('me')){$uid = $row['id'];$cover = $row['cover'];$fname = $row['name'];$mname = $row['name2'];$like = $row['likes'];}
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加了这个b.month= $month条件之后A表里的数据($uid $cover $fname $mname)不显示了,要求只是$like根据$month这个变化

你的连接条件是 a.id=b.id
你的过滤条件是  b.month= $month
没有结果,就表示 b 中没有符合条件的记录

那么,你的 b.month 是数值型的吗?

感谢再次耐心解答。

你的连接条件是 a.id=b.id
你的过滤条件是  b.month= $month
没有结果,就表示 b 中没有符合条件的记录

那么,你的 b.month 是数值型的吗?


嗯,b.month 是数值型int
还是不懂,b中没符合条件的记录,但是a里面的变量也输出不了数据
现在我的目的是查询输出a表的数据,b表只查寻以month 为条件的likes字段没有就输出0
不知道是我代码问题还是sql问题,新手好难

这种情况 要不你就在后面写  反正已经按照a.id进行排序了

如果 你硬要按照b.month= $month来   那就只能再写一句

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