Do you want to store the order information in the database as well? If not you can just remove the "Store cart summary" and "Store cart details" server behaviors on the success page.
The error appears to be because you are using text values as the ProductID and the insert details server behavior has the ProductID field defined in the database and server behavior as numeric. You could probably fix it by updating the column type in the orderdetails table for the ProductID to be varchar(50) and then update the store cart summary in database server behavior to specify that field as a text data type on the php page as well.