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', 's7jsctkklq8pvsvqlll78gacg2', '216.73.216.145', '1778154270', '1778154270', '/index.php?XTCsid=ec34e8689ca02683c909010c614b53e3')

[XT SQL Error]