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', 'uqa6bf4jce1iko61f2c2gna012', '18.97.14.85', '1776597535', '1776597535', '/xtshop/index.php')

[XT SQL Error]