List Customer and Product Without Sale

Using the UNION operator, in one list return all customers who do no have an invoice and all products that were not sold.

For each customer without an invoice, return:

the string customer

the customer id

the customer$\_$name

For each product without an invoice, return:

the string product

the product id

the product$\_$name

The columns must be in the order shown, but row order does not mutte