Removing the ProductID field is not an option for this template. It is a key part of the system and what enables you to select a product from the products table. You really do need this field in order for the invoicing to work correctly. This is true even if you don't need the number for any other purposes.
This is a typical feature of Relational Databases that you have fields serving as keys to link records but the value in the field itself has no meaning to the user except for the fact that the value uniquely identifies a record in one of the tables in the database. In the case of the invoices starter solution, this product ID uniquely identifies records in the product table and that's what enables the data base to select the correct product descriptoion and pricing information from the products table.
Thank you for answering so quickly. OK so I need the ProductID field. What is the solution? Do I start over or can I just make the Product name the field which serves as a key to link records? Starting over would be very unfortunate as I have put a lot of work into the database already.
It's possible to use the Product Name, but I don't recommend doing so. That can create issues for you should you decide to update product names in the future.
Did you just remove this field from the layout or did you delete the field definition?
If you just removed it from the layout, you can easily put it back. You can even open a new copy of the invoices starter solution, enter layout mode and then copy and paste the field and it's formatting back into your layout.
If you removed the field from the Products and/or the lineItems table, you have more work to do to put it back.
If you don't have a back up copy you can revert to that doesn't have this change, you can redefine the ProductID field in both tables, specifying that ProductID in the products table be an auto-entered serial number. If you have product records already entered into the products table, you can use Replace Field Contents to assign serial numbers to your existing product records.
Once you have these fields back in the product tables, you can use Manage | Database | Relationships to reconnect the Product and LineItem tables by ProductID. You can refer to a new copy of the the Invoicing solution to make sure that you've correctly re-established the relationships.
Thank you. I managed to find a back up and just startd over.