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', '15i4pnn6mp2t9ncroct7c92qc6', '216.73.216.110', '1752051246', '1752051246', '/shop_content.php?coID=4&XTCsid=502c4d4f7753d1888d9a6ca985d5c9c9')

[XT SQL Error]