我在zendFramework2中有一个不工作的查询,它显示未知列我的查询$select=newSelect('dining_table_reservation');$select->columns(array('range'=>new\Zend\Db\Sql\Expression("CONCAT(5*floor(dining_table.SeatingCapacity/5),'-',5*floor(dining_table.SeatingCapacity/5)+5)"),'Avgtime'=>new\Zend\Db\Sql\Expression('avg(timestampdiff(