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', '1npsit084qai1pacmffkbr0442', '216.73.216.180', '1766401500', '1766401500', '/index.php?XTCsid=d3f81aac1b90a5822d8663a3af39931e&cat=c5_Crockery.html')

[XT SQL Error]