Here is a sample SQL of how one could find multiple rows.

Example: Using HAVING count(*) > 1

SELECT A.EMPLID,
COUNT(A.EMPLID) AS NumOccurrences
FROM PS_PERS_NID A
GROUP BY A.EMPLID
HAVING ( COUNT(A.EMPLID) > 1 )

Read further:

http://jmcmahon33.blogspot.com/2012/03/sql-to-find-duplicates-sampl...