WordPress at a glance
function is not described

network_domain_check() WP 3.0.0

Check for an existing network.

  • Global. wpdb. $wpdb WordPress database abstraction object.

No Hooks.

Return

String/false. Base domain if network exists, otherwise false.

Usage

network_domain_check();

Code of network domain check: wp-admin/includes/network.php WP 5.2.2

<?php
function network_domain_check() {
	global $wpdb;

	$sql = $wpdb->prepare( 'SHOW TABLES LIKE %s', $wpdb->esc_like( $wpdb->site ) );
	if ( $wpdb->get_var( $sql ) ) {
		return $wpdb->get_var( "SELECT domain FROM $wpdb->site ORDER BY id ASC LIMIT 1" );
	}
	return false;
}