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', '70nucrc6oubtbemje5pirh48b4', '216.73.216.87', '1765914091', '1765914091', '/product_info.php?XTCsid=f6e58886be8011b1d9a8e232c116cb7a&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]