I have a database that accepts first and last name entries for a primary person and a secondary person.  However, there is a problem that sometimes the secondary person comes back looking to be entered as a separate primary person, which is not permitted.  However, I do not have any data validation or verification to prevent this.  When a new record is created, would I be able to use SQL to check the first and last name combinations entered for the primary and the secondary persons against the names previously entered in the database and create a dismissible dialog popup giving a warning when duplicate names are entered?  Ideally the dialog box would also give a link to go to the record where the duplicate name was previously entered to verify that the individual is the same.

Why use SQL for this?

I'd also point out that FirstName / LastName isn't a unique combination anyway - there are several Peter Booth's in my wider family for a start...

If I were to go down this path, then a simple search on FirstName / LastName with a found count of > 0 should suffice