=$db->createCommand($sql)->query()返回结果是什么?

$sql=“select * from {{blog_video}} where md5=:md5 limit 1;”; $videoExist=$db->createCommand($sql)->query(array(’:md5’=> $md5));

返回值是

okCDbDataReader Object ( [_statement:CDbDataReader:private] => PDOStatement Object ( [queryString] => select * from qijunz_blog_video where md5=:md5 limit 1; ) [_closed:CDbDataReader:private] => [_row:CDbDataReader:private] => [_index:CDbDataReader:private] => -1 [_e:CComponent:private] => [_m:CComponent:private] => )

为什么? 我怎么得到 查询结果

请细看guide中的DAO一节介绍几种查询方式的返回值。