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', 'n6gttaoq212prs4hui9tph9gh4', '216.73.216.165', '1752396075', '1752396075', '/product_info.php?info=p17_20-Tissue-Napkins.html&XTCsid=75dc59d6a30660e0992222d2318ca53e')

[XT SQL Error]