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', '23e63ccc5e88fc6ad07a2a38adc42e2c', '54.158.138.161', '1711694875', '1711694875', '/newsletter.php')

[XT SQL Error]