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', 'pmfoj2dmcol73dtqegfl7rfe21', '3.17.57.190', '1746999754', '1746999754', '/xtshop/product_info.php?info=p1076_.html')

[XT SQL Error]