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', '5m7joqll3papssoh1ql0v7ib95', '216.73.216.110', '1752058901', '1752058901', '/product_info.php?info=p17_20-Tissue-Napkins.html&XTCsid=502c4d4f7753d1888d9a6ca985d5c9c9')

[XT SQL Error]