function wc_update_330_product_stock_status() {
	global $wpdb;

	if ( 'yes' !== get_option( 'woocommerce_manage_stock' ) ) {
		return;
	}

	$min_stock_amount = (int) get_option( 'woocommerce_notify_no_stock_amount', 0 );

	// Get all products that have stock management enabled, stock less than or equal to min stock amount, and backorders enabled.
	$post_ids = $wpdb->get_col(
		$wpdb->prepare(
			"SELECT t1.post_id FROM $wpdb->postmeta t1
			INNER JOIN $wpdb->postmeta t2
				ON t1.post_id = t2.post_id
				AND t1.meta_key = '_manage_stock' AND t1.meta_value = 'yes'
				AND t2.meta_key = '_stock' AND t2.meta_value <= %d
			INNER JOIN $wpdb->postmeta t3
				ON t2.post_id = t3.post_id
				AND t3.meta_key = '_backorders' AND ( t3.meta_value = 'yes' OR t3.meta_value = 'notify' )",
			$min_stock_amount
		)
	); // WPCS: db call ok, unprepared SQL ok, cache ok.

	if ( empty( $post_ids ) ) {
		return;
	}

	$post_ids = array_map( 'absint', $post_ids );

	// Set the status to onbackorder for those products.
	$wpdb->query(
		"UPDATE $wpdb->postmeta
		SET meta_value = 'onbackorder'
		WHERE meta_key = '_stock_status' AND post_id IN ( " . implode( ',', $post_ids ) . ' )'
	); // WPCS: db call ok, unprepared SQL ok, cache ok.
}