请问使用php的pdo查询出来怎么会是空白？

我有一个php是这样写的：

<?phprequire('inc/pdo.php');$lt=$dbc->prepare(" select b.subject from pre_forum_forum a inner join pre_forum_forum aa on a.fid=aa.fup inner join pre_forum_thread b on b.fid=aa.fid where a.name='你好'");$lt->execute();while($row=$lt->fetch()){print_r($row);};?>

打开页面是一片空白，本以为是写错了，就换了一个sql语句：
select * from tablename 


这样就正常，请教大神这是为什么？

回复讨论(解决方案)

这个sql语句已经跑过，没有错！

求大神啊。。。。

from pre_forum_forum a
可以直接from a


a.name='你好'
有字符集问题。

如果pdo 对应的mysql 版本不对，会有这个bug

如果pdo 对应的mysql 版本不对，会有这个bug
我这个是对的啊

$arr = $lt->errorInfo();
print_r($arr); //这样看看

$arr = $lt->errorInfo();
print_r($arr); //这样看看

<?phprequire('inc/pdo.php');//$wlt='你好';$lt=$dbc->prepare("select b.subject from pre_forum_forum a inner join pre_forum_forum aa on a.fid=aa.fup inner join pre_forum_thread b on b.fid=aa.fid where a.name='你好'");//$lt->execute(array($wlt));//while($row=$lt->fetch()){//print_r($row);//};$arr = $lt->errorInfo();print_r($arr); ?>

结果是：
Array ( [0] => [1] => [2] => )

把上面的注释全部删掉再试

把上面的注释全部删掉再试

<?phprequire('inc/pdo.php');$wlt='你好';$lt=$dbc->prepare("select b.subject from pre_forum_forum a inner join pre_forum_forum aa on a.fid=aa.fup inner join pre_forum_thread b on b.fid=aa.fid where a.name=?");$lt->execute(array($wlt));while($row=$lt->fetch()){print_r($row);};$arr = $lt->errorInfo();print_r($arr); ?>

结果还是：Array ( [0] => 00000 [1] => [2] => )

Array ( [0] => 00000 [1] => [2] => )
表示没有语法错，但不表示一定有结果
你的查询条件是中文的，那么就有一个字符集问题
字符集不对，就查不到了

另外就常理而言
a.name='你好'
你不觉得有点怪异吗？

可能是字符集问题，在prepare前面加上
$dbc->query('set names utf8');   

Array ( [0] => 00000 [1] => [2] => )
表示没有语法错，但不表示一定有结果
你的查询条件是中文的，那么就有一个字符集问题
字符集不对，就查不到了

另外就常理而言
a.name='你好'
你不觉得有点怪异吗？
这个只是数据库起的别名， 问题解决了                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        

我就说有字符集问题。你不听