using if/then and using sorting to parse data and create list without spaces

I am looking to use a sales database to create an invoice. i would like to use a y/n flag under an invoice column which would determine that an invloice would be populated with data for that customer from the sales database. there are many products and not always a sale of each item so there are lots of products that will need to be left off the invoice.

What i would like is to create an invoice that lists the products purchased. i have included a sample of what the sales database looks like.

The invoice will list the items vertically.