Zend_Db_Select ordem aleatória, compatível em mssql/mysql

class MyTable extends Zend_Db_Table_Abstract {
   public function randomSelect($select=null) {
     if ($select === null) $select = $this->select();
     if (!$select instanceOf Zend_Db_Select) $select = $this->select($select);
     $adapter = $this->getAdapter();
     if ($adapter instanceOf Zend_Db_Adapter_Mysqli) {
       $select->order(new Zend_Db_Expr('RAND()'));
     } else if ($adapter instanceOf Zend_Db_Adapter_Dblib) {
       $select->order(new Zend_Db_Expr('NEWID()'));
     } else { 
       throw new Exception('Unknown adapter in MyTable');
     }
     return $select;
  }
}

$someSelect = $table->select();
// add it to an existing select
$table->randomSelect($someSelect);

// or create one from scratch
$select = $table->randomSelect();

$select->order(new Zend_Db_Expr('0*`id`+RAND()));