private function expressionRun($table, $field, $type, $index)
    {

        if ($type === Column::TYPE_TEXT) {

            // match query
            $query = "MATCH(" . $table . "." . $field . ") AGAINST (:query:)";

        }
        else {

            // simple query
            $query = $table . "." . $field . " LIKE :query:";
        }

        if ($index > 0) {
            $this->builder->orWhere($query, $this->ftFilter($type));
        }
        else {
            $this->builder->where($query, $this->ftFilter($type));
        }

        return null;
    }