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', 'gt140h3e0jre87c6mqqdpjkfv1', '216.73.216.110', '1752972063', '1752972063', '/product_info.php?info=p17_20-Tissue-Napkins.html&XTCsid=502c4d4f7753d1888d9a6ca985d5c9c9')

[XT SQL Error]