Same Fields SQL

I need help with a query/subquery:
I’m trying to find duplicate patients, where 3 fields are the same:
PATIENTNAME=PATIENTNAME AND BIRTHDATE=BIRTHDATE AND DIAGNOSEDATE=DIAGNOSEDATE , like these:

  1. John, 01/01/2001, 01/09/2010
  2. John, 01/01/2001, 01/09/2010
  3. Doe, 09/01/2001, 01/01/2015
  4. Doe, 09/01/2001, 01/01/2015
    and so on.
    Thank you, very much!

I think it’s explained in: