UPDATE on INSERT duplicate primary key in Oracle?

Question

I have a simple INSERT query where I need to use UPDATE instead when the primary key is a duplicate. In MySQL this seems easier, in Oracle it seems I need to use MERGE.

Answer 1

MERGE is the 'do INSERT or UPDATE as appropriate' statement in Standard SQL, and probably therefore in Oracle SQL too.

Yes, you need a 'table' to merge from, but you can almost certainly create that table on the fly:

 MERGE INTO Movie_Ratings M
       USING (SELECT 1 AS mid, 3 AS aid, 8 AS rating FROM dual) N
          ON (M.mid = N.mid AND M.aid = N.aid)
       WHEN     MATCHED THEN UPDATE SET M.rating = N.rating
       WHEN NOT MATCHED THEN INSERT(  mid,   aid,   rating)
                             VALUES(N.mid, N.aid, N.rating);

(Syntax not verified.)