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', 'cb54acd32d9b32f404296b17d7a02b44', '216.73.216.42', '1763383908', '1763383908', '/shop/product_info.php?info=p149_.html')

[XT SQL Error]