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', '6783aa2e1bf7888c40976f2b1d50278d', '216.73.216.42', '1763354998', '1763354998', '/shop/index.php?cPath=9')

[XT SQL Error]