protected function sql_orderby() {

		$sql = '';

		$sort = $this->get( 'sort' );
		if ( $sort ) {

			$sql = 'ORDER BY';

			$comma = false;

			foreach ( $sort as $orderby => $order ) {
				$pre   = ( $comma ) ? ', ' : ' ';
				$sql  .= $pre . "{$orderby} {$order}";
				$comma = true;
			}
		}

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

		/**
		 * Filters the query ORDER BY clause.
		 *
		 * The dynamic part of the filter `$this->id` identifies the extending query.
		 *
		 * @since 3.8.0
		 *
		 * @param string              $sql      The ORDER BY clause of the query.
		 * @param LLMS_Database_Query $db_query The LLMS_Database_Query instance.
		 */
		return apply_filters( "llms_{$this->id}_query_orderby", $sql, $this );

	}