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', 'q4ptc2l1v0dahnr5kqtfr30u06', '216.73.216.127', '1752882162', '1752882162', '/index.php?XTCsid=a1e615fe261b6ebee1d6d44580f7a3af')

[XT SQL Error]