I am new to databases and thus to Access. I have a situation where I am
trying to figure out how to key some tables I am working with. Consider that
I have a database of my own records which are invoices I work on. These
invoices are from four companies with their own invoice numbers. So, I
cannot key by invoice number because there is a likelihood of invoice
numbers duplicated by different companies. The records in this table of
joined invoices are referenced in other tables, and I am not fond of using a
created index to reference each record.

Is it possible in Access (and SQL) to set the primary key to be a composite
of two columns? If so, how do I create a relationship between that table and
other tables? Say I have a separate table that keeps track of whether I've
been paid for processing each invoice. I would like to use the company name
and the company invoice number to create the relationship instead of my own
fabricated index. However, I'm not sure whether that can be done, never mind
the question of whether it is a good idea.

Thanks for the help, folks!

Paul