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', '6vhnnv6pfnjamio1a38rn73ea4', '216.73.216.241', '1786710964', '1786710964', '/xtshop/create_account.php')

[XT SQL Error]