Oracle: how to UPSERT (update or insert into a table?)

Question

The UPSERT operation either updates or inserts a row in a table, depending if the table already has a row that matches the data:

if table t has a row exists          


        

Answer 1

I'd like Grommit answer, except it require dupe values. I found solution where it may appear once: http://forums.devshed.com/showpost.php?p=1182653&postcount=2

MERGE INTO KBS.NUFUS_MUHTARLIK B
USING (
    SELECT '028-01' CILT, '25' SAYFA, '6' KUTUK, '46603404838' MERNIS_NO
    FROM DUAL
) E
ON (B.MERNIS_NO = E.MERNIS_NO)
WHEN MATCHED THEN
    UPDATE SET B.CILT = E.CILT, B.SAYFA = E.SAYFA, B.KUTUK = E.KUTUK
WHEN NOT MATCHED THEN
    INSERT (  CILT,   SAYFA,   KUTUK,   MERNIS_NO)
    VALUES (E.CILT, E.SAYFA, E.KUTUK, E.MERNIS_NO);