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', '4n8jcmtm1ddrkt2hlmo2r076s2', '18.97.14.85', '1754850820', '1754850820', '/xtshop/product_info.php?info=p1116_.html')

[XT SQL Error]