1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, session_id, ip_address, time_entry, time_last_click, last_page_url) values ('', 'Guest', '4jl5dks8kok79h8suqggv2dg53', '216.73.216.155', '1767579086', '1767579086', '/index.php?XTCsid=68ade1b37223d7a85541797e5ace892d')

[XT SQL Error]