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', '5ausrc6r4rn9ko57d9npqjvb34', '216.73.216.70', '1752613254', '1752613254', '/index.php?cat=c5_Crockery.html&XTCsid=85f438a686cbfb5e3ea5e5d6b9611958')

[XT SQL Error]