数据库类方法不返回结果

Question

I have looked and can not find what I am doing wrong here. I have a database class I created with the following method:

public function db_fetch_dataset($sql_qry)
{
    $log= new log_class;
    $db_conn = self::_connect();
    try{        
        $results = $db_conn->query($sql_qry);
        return $results;
    }catch(PDOException $e){            
        log_class::save_to_log($e,__LINE__,__FILE__);   
    }    
    $db_conn = null;
}

I am using it here:

$db= new database_class;
$sql_parties ="SELECT (SELECT political_party
                         FROM political_party_tbl
                        WHERE political_party_abbr = PARTY) as PARTY
                       ,count_of_voters
               FROM vrm_count_of_registered_voters_by_party_vw
             ORDER BY PARTY";

$results = $db->db_fetch_dataset($sql_parties); 

while($row= $results ->fetch(PDO::FETCH_ASSOC)) 
{
echo "<h4>".$row['PARTY'].": ".number_format($row['count_of_voters'])."</h4>
";
}

I am getting the following error: "Fatal error: Call to a member function fetch() on a non-object"

Would someone be kind enough to tell me what I am doing wrong or direct me to the answer? Thanks!!

Added- fyi: the query itself is not causing the error. It runs fine in SQL Server Manager.

Answer 1

Ok, got it working. Here is what worked:

public function db_fetch_dataset($sql_qry)
{
   $log= new log_class;
   $db_conn = self::_connect();

   try{    
    $exec_str= $db_conn->prepare($sql_qry);
        $exec_str->execute();
        return $exec_str;
       }catch(PDOException $e){         
        $log->save_to_log($e,__LINE__,__FILE__);    
       }    
    $db_conn = null;
}

and

$db= new database_class;    
$sql_parties ="SELECT (SELECT political_party
  FROM political_party_tbl
  WHERE political_party_abbr = PARTY) as PARTY
  ,count_of_voters
FROM vrm_count_of_registered_voters_by_party_vw
ORDER BY PARTY";

$results = $db->db_fetch_dataset($sql_parties); 

while($row= $results ->fetch(PDO::FETCH_ASSOC)) 
{       
       echo "<h4>".$row['PARTY'].": ".number_format($row['count_of_voters'])."</h4>
";
}