how to check data in a certain location

Hi all,

I need to compare and match two fields, the data can be in following manner:

first_name/tableA first_name/tableB

Diana R Diana

Diana Diana Rosa

Diana R Diana R

Diana Patrick

My result should find only Diana and Patrick as nonmatch and all other as match.

How should I write the query?

Thanks in advance!!

Are you trying to find whether first name in Table A does not exist in table B?

select firstname
from tableA
where firstname not in (
select firstname from tableB)