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', 'pvbagrit3utl32qq6feefed1s7', '18.188.180.227', '1746768340', '1746768340', '/xtshop/index.php?cat=c59_.html')

[XT SQL Error]