GetChildren($objID);

Sub GetChildren{
  ($objid)=@_;
  my $sth = $dbh->prepare("select objid,type from table where  parentid=?")
  $sth->execute($objid)
  while (@row = $sth->fetchrow_array){
      ($objid, $type)=@row;
      if($type="Container"){
         GetChildren($objid);
      }else{
         do something else
      }
  }