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', 'e3pvjk5k1bu95cpma96b20hl42', '216.73.217.35', '1779106775', '1779106775', '/xtshop/product_info.php?info=p963_.html')

[XT SQL Error]