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', 'pg7e1i7tt33mtsv1k43992p921', '18.232.53.231', '1566150962', '1566150962', '/product_info.php/info/p6_TDI-Advanced-Nitrox---Decompression-Procedures-Manual--deutsch-.html')

[XT SQL Error]