1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, ip_address, time_last_click, last_page_url, time_entry, session_id, http_referer) values ('', '[TEXT_SEARCH_ENGINE_AGENT]', '54.234.228.78', '1544862942', '/GewAOErzmischungen/WAOErzsalze:::1303_1327.html', '1544862942', '', '---')

[XT SQL Error]