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', '5u9vciefno1orvrlu02nchqc26', '54.224.255.158', '1498515481', '1498515481', '/product_info.php?info=p132_Da-war-mal-was---.html&XTCsid=h84gj4ie5gil7kbps97mfctho1')

[XT SQL Error]