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', '151e3628e6f26460bf2c37b894cdf9a4', '216.73.217.75', '1789292210', '1789292210', '/shop/index.php?cPath=9_6_24')

[XT SQL Error]