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, http_referer) values ('', 'Guest', '70qmd119fna6bb9cu90k4vuhh7', '172.17.6.186', '1454726287', '1454726287', '/shop/product_info.php?info=p1142_06-12-2012-STONE-SOUR---PAPA-ROACH--Oberhausen-.html', '')

[XT SQL Error]