Oracle sql merge to insert and delete but not update

Question

Is there a way to use oracle merge to insert and delete but not update?

I have a table representing a set of values related to a single row in another table. I coul

Answer 1

I have found you can set the column to itself:

MERGE ...
WHEN MATCHED THEN 
   UPDATE SET a_value = a_value WHERE a_value not in ('ace','afk')
   DELETE WHERE a_value not in ('ace','afk')

This negates the need for the dummy column.