WordPress at a glance
function is not described

wc_reset_order_customer_id_on_deleted_user() WC 1.0

Reset _customer_user on orders when a user is deleted.

No Hooks.

Return

null. Nothing.

Usage

wc_reset_order_customer_id_on_deleted_user( $user_id );
$user_id(int) (required)
User ID.

Code of wc_reset_order_customer_id_on_deleted_user() WC 5.3.0

<?php
function wc_reset_order_customer_id_on_deleted_user( $user_id ) {
	global $wpdb;

	$wpdb->update(
		$wpdb->postmeta,
		array(
			'meta_value' => 0,
		),
		array(
			'meta_key'   => '_customer_user',
			'meta_value' => $user_id,
		)
	); // WPCS: slow query ok.
}