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', '5di1h2fmfgn2ea1ifrs9f1skn7', '216.73.216.147', '1751764513', '1751764513', '/product_info.php?info=p11_Fan-for-decorations.html&XTCsid=ca28ab8f46bb6e791b42fe9b92719761')

[XT SQL Error]