public function get_on_sale_products() {
		global $wpdb;

		$exclude_term_ids            = array();
		$outofstock_join             = '';
		$outofstock_where            = '';
		$non_published_where         = '';
		$product_visibility_term_ids = wc_get_product_visibility_term_ids();

		if ( 'yes' === get_option( 'woocommerce_hide_out_of_stock_items' ) && $product_visibility_term_ids['outofstock'] ) {
			$exclude_term_ids[] = $product_visibility_term_ids['outofstock'];
		}

		if ( count( $exclude_term_ids ) ) {
			$outofstock_join  = " LEFT JOIN ( SELECT object_id FROM {$wpdb->term_relationships} WHERE term_taxonomy_id IN ( " . implode( ',', array_map( 'absint', $exclude_term_ids ) ) . ' ) ) AS exclude_join ON exclude_join.object_id = id';
			$outofstock_where = ' AND exclude_join.object_id IS NULL';
		}

		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		return $wpdb->get_results(
			"
			SELECT posts.ID as id, posts.post_parent as parent_id
			FROM {$wpdb->posts} AS posts
			INNER JOIN {$wpdb->wc_product_meta_lookup} AS lookup ON posts.ID = lookup.product_id
			$outofstock_join
			WHERE posts.post_type IN ( 'product', 'product_variation' )
			AND posts.post_status = 'publish'
			AND lookup.onsale = 1
			$outofstock_where
			AND posts.post_parent NOT IN (
				SELECT ID FROM `$wpdb->posts` as posts
				WHERE posts.post_type = 'product'
				AND posts.post_parent = 0
				AND posts.post_status != 'publish'
			)
			GROUP BY posts.ID
			"
		);
		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
	}