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', 'oku1k36h5vrcf2ra930m5dg3h4', '216.73.216.63', '1773898257', '1773898257', '/index.php?XTCsid=6cde0892201ba4318d3281510fa30ce4')

[XT SQL Error]