How to update data in wordpress database table with functions.php?

How to update data in wordpress database table with functions.php?

	global $wpdb;
	$quotetable = $wpdb->prefix . "quote";	
        $where = array(
			'ID' => $id
		);	
	$wpdb->update( $quotetable,
		array(
		'useremail' => $useremail,
		'quote_no' => "123",
		'product_ids' => "1,2,3"
		), $where
	);