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', 'ois8avg2a6nshpui72fj694a75', '216.73.217.120', '1793603704', '1793603704', '/index.php?XTCsid=23380c0ea5ceb30ea6ad18aac0802b89')

[XT SQL Error]