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', '3cae8cr187p5aqeqlct27f9rs4', '216.73.216.147', '1751961439', '1751961439', '/shop_content.php?coID=3&XTCsid=e990f3916c880610adc34c2fa7d30f83')

[XT SQL Error]