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', '5217d5b473f216ae29528dbe2c6de14b', '34.229.24.100', '1563487741', '1563487741', '/index.php/cat/c10_Calvin-Klein.html')

[XT SQL Error]