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', '8hjbrinpbd6knhfgthuhv0t1n0', '3.236.108.61', '1594164040', '1594164040', '/shop/index.php')

[XT SQL Error]