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', '7pcltc9g9t05ssokapp9geoc77', '216.73.216.31', '1774935356', '1774935356', '/index.php?XTCsid=d0fb6f95a363340d124d7dc76e615e44&cat=c5_Crockery.html')

[XT SQL Error]