Anyone know how to enforce uniqueness in 2 columns (or more) in an Excel worksheet...inda like a primary key?

Maybe Uniqueness is an alien word....

Sure... so the combination across x number of columns needs to be unique?

If the user is manually entering into the columns then you can use data validation. If the values are to be calculated by formulas then you could create an autonumbering system.

If you elaborate a bit on the requirements and confirm your Excel version then I should be able to whip up an example for you?