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', 'bpc3edtfmpoie49rlmkorqro73', '3.85.92.139', '1561470203', '1561470203', '/index.php/language/en')

[XT SQL Error]