InfoPath Dev

I'm submitting to an Access database, so my expectation is that a new record would be created, or if I violate primary key rules, I would get an error, and the submission would fail.  This is the behavior if I fill out a new form from the template and submit.  What I'm trying to figure out is how InfoPath knows what record ...

I posted earlier and didn't get any replies, so let me try and simplify my question and maybe that will help me better articulate the rest... I'm trying to figure out how InfoPath links to the Access database, specifically, how does it know what record to update?  I have a form, and I've filled it out, saved it, submitted it, ...

Hoping someone on here can give me a couple pointers on an InfoPath form that I have a data connection to an access database to submit the form data to. I have never used InfoPath, so I've been learning as I go, so bear with me here... My quesiton is around how InfoPath decides when to create a new record vs when to update an existing record ...