[HELP]: SQL code assistance

As a new Oracle sql writer, I was wondering if someone could pass along to me some sample code that will take a selection of multiple records and process them one at a time.

I have Social Security numbers in two tables, TABLE-A and TABLE-B. I would like to scan the records in TABLE-B to a match in TABLE-A. Based on the result, I would like to do some processing, like: if match do this, if no match, add a new record.

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Neil Greene
President, benchMark Developments, Inc. [NeXT VAR]
President, Kentucky NeXT User Group, Inc.
North American, TIFFany Distributor