WordPress at a glance
function is not described

wpdb::close() public WP 4.5.0

Closes the current database connection.

{} It's a method of the class: wpdb{}

No Hooks.

Return

true/false. True if the connection was successfully closed, false if it wasn't, or if the connection doesn't exist.

Usage

global $wpdb;
$wpdb->close();

Changelog

Since 4.5.0 Introduced.

Code of wpdb::close() WP 5.5.1

<?php
public function close() {
	if ( ! $this->dbh ) {
		return false;
	}

	if ( $this->use_mysqli ) {
		$closed = mysqli_close( $this->dbh );
	} else {
		$closed = mysql_close( $this->dbh );
	}

	if ( $closed ) {
		$this->dbh           = null;
		$this->ready         = false;
		$this->has_connected = false;
	}

	return $closed;
}