MERGE
を使用する必要があります 。のようなもの
MERGE INTO users dest
USING( SELECT 1 user_id, 10 points FROM dual) src
ON( dest.user_id = src.user_id )
WHEN MATCHED THEN
UPDATE SET points = src.points
WHEN NOT MATCHED THEN
INSERT( user_id, points )
VALUES( src.user_id, src.points );