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', '34bar7l3cidcvpt1mun7ig4n20', '216.73.216.87', '1765597936', '1765597936', '/product_info.php?XTCsid=3e3fcef0642c69bbf707de3c0bc1cf9c&info=p14_65-drinking-cups-1-2-Liter.html')

[XT SQL Error]