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', '0lslq2g98qa18554pmjhv74me0', '216.73.217.152', '1791031203', '1791031203', '/product_info.php?XTCsid=38f09672db884903e3803adf9d076819&info=p21_Paper-tablecloth-10-meters.html')

[XT SQL Error]