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', '6asga4fl5jq5dl9rk97p69lan3', '216.73.216.244', '1752201280', '1752201280', '/product_info.php?info=p2_Bavarian-Pennant-Chain.html&XTCsid=38f09672db884903e3803adf9d076819')

[XT SQL Error]