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', 'm5cipn5l37pha9u8hegl8vaua2', '216.73.216.26', '1770220611', '1770220611', '/index.php?XTCsid=0832187515ca706758d8e1ce01e34faf&cat=c5_Crockery.html')

[XT SQL Error]