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', 'es8auj5ku9e2r28ml0gk6qv6h2', '3.133.129.9', '1747000697', '1747000697', '/xtshop/product_info.php?info=p544_.html')

[XT SQL Error]