symfony - Symfony2/Doctrine2 issue with query -

i getting weird response query messing things up. essentially, make call so

$allflights = $em->getrepository("nickalertbundle:alert")->getspecificalert($id); 

this calls following query

public function getspecificalert($id) {     $active = "active";      return $this->getentitymanager()         ->createquery(             'select a.id, a.searchcommand,                 group_concat(distinct c.classletter) classes,                 group_concat(distinct p.pseudo) pseudos,                 group_concat(distinct f.flightnumber) flight_number                     nickalertbundle:alert                         join nickalertbundle:bookingclass c                           a.id = c.availabilityalert                         join nickalertbundle:pseudos p                           a.id = p.availabilityalert                         join nickalertbundle:flightnumbers f                           a.id = f.availabilityalert                     a.alertstatus = :active                     , a.id = :id                     group a.id'         )         ->setparameter('active', $active)         ->setparameter('id', $id)         ->getresult(); } 

now in database have 2 alerts. if var_dump response query, first alert

array(1) {      [0]=> array(5) {          ["id"]=> int(3)          ["searchcommand"]=> string(12) "a20junlonmia"          ["classes"]=> string(1) "i"          ["pseudos"]=> string(7) "12d,4fd"          ["flight_number"]=> string(6) "ay5507"      }  }  

now 1 processes fine. if output second alert following

array(1) {      [0]=> array(5) {          ["id"]=> int(8)          ["searchcommand"]=> string(20) "@ba@a20aprlonnyc0100"          ["classes"]=> string(1) "a"          ["pseudos"]=> string(7) "12d,4fd"          ["flight_number"]=> string(6) "ba1516"      }  }  array(0) { }  

so empty array on end. there 1 alert id in database, not sure why happening. anyways, empty array causing following fail

$command = $allflights[0]['searchcommand']; 

is there reason why may receiving empty array particular query? seems occur command starts @.

thanks