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', 'c6ef3eca1ada11461f3625ef92290c36', '216.73.216.42', '1763354953', '1763354953', '/shop/index.php?cPath=9_5')

[XT SQL Error]