I got this error as I was updating information for a product, the information I was updating (adding actually) was shipping methods and package specs. I tried submitting a page without editing it contents and got the same error.
It should be noted that I over wrote the old ecommerce install after a security rik was found in the store module.
* user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '0 = '' WHERE vid = 46' at line 1 query: UPDATE ec_product SET nid = '46', vid = '46', pparent = '0', sku = '', price = '4.95', is_recurring = '0', price_interval = '0', price_unit = '', price_cycle = '0', auto_charge = '0', ptype = 'tangible', hide_cart_link = '0', 0 = '' WHERE vid = 46 in /home/mysite/public_html/subdomain/includes/database.mysql.inc on line 120.
* user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '0 = '' WHERE vid = 46' at line 1 query: UPDATE ec_product SET nid = '46', vid = '46', pparent = '0', sku = '', price = '4.95', is_recurring = '0', price_interval = '0', price_unit = '', price_cycle = '0', auto_charge = '0', ptype = 'tangible', hide_cart_link = '0', 0 = '' WHERE vid = 46 in /home/mysite/public_html/subdomain/includes/database.mysql.inc on line 120