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', 'd5udcf97dsl942532s2lh5q5g1', '3.15.10.50', '1747129437', '1747129437', '/xtshop/product_info.php?info=p893_.html')

[XT SQL Error]