Bookings/Registration metabox: Booked Spaces Count

<?php

function my_get_ticket_booked_spaces( $booked_spaces, $EM_Ticket ){
	global $wpdb;

	$table_name    = $wpdb->prefix.'em_tickets_bookings';
	$table_booking = $wpdb->prefix.'em_bookings';
	$booked_spaces = $wpdb->get_var('
										SELECT SUM(t.ticket_booking_spaces) AS booked_space
										FROM '.$table_name.' t
										LEFT JOIN '.$table_booking.' b  ON t.booking_id = b.booking_id
										WHERE
										b.booking_status = 1 AND
										t.ticket_id='. absint($EM_Ticket->ticket_id) .' GROUP BY t.ticket_id');

	return $booked_spaces;
}
add_filter('em_ticket_get_booked_spaces', 'my_get_ticket_booked_spaces', 100, 2 );