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', '045f6b0f8abffaf45dd509c62376a9a1', '216.73.217.165', '1780980670', '1780980670', '/shop/index.php?cPath=3')

[XT SQL Error]