使用原则 2 执行原始 SQL

以下是我正在做的教义 2 中的原始查询示例：

public function getAuthoritativeSportsRecords()
{   
    $sql = " 
        SELECT name,
               event_type,
               sport_type,
               level
          FROM vnn_sport
    ";

    $em = $this->getDoctrine()->getManager();
    $stmt = $em->getConnection()->prepare($sql);
    $stmt->execute();
    return $stmt->fetchAll();
}   

//$sql - sql statement
//$em - entity manager

$em->getConnection()->exec( $sql );