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', 'm5hicdqr4lti74f59kn69cq8c7', '216.73.216.87', '1765810660', '1765810660', '/index.php?XTCsid=b2f2fd5328d88ea7ac143d7fb7715fbe')

[XT SQL Error]