protected function sql_select_columns( $select_columns = '*' ) {

		if ( ! $this->get( 'no_found_rows' ) ) {
			$select_columns = 'SQL_CALC_FOUND_ROWS ' . $select_columns;
		}

		if ( $this->get( 'suppress_filters' ) ) {
			return $select_columns;
		}

		/**
		 * Filters the query SELECT columns.
		 *
		 * The dynamic part of the filter `$this->id` identifies the extending query.
		 *
		 * @since 4.5.1
		 *
		 * @param string              $select_columns Columns to select.
		 * @param LLMS_Database_Query $db_query       Instance of LLMS_Database_Query.
		 */
		return apply_filters( "llms_{$this->id}_query_select_columns", $select_columns, $this );

	}