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

A typical way of doing this is

• performing the INSERT and catch a DUP_VAL_ON_INDEX and then perform an UPDATE instead
• performing the UPDATE first and if SQL%Rows = 0 perform an INSERT

You can't write a trigger on a table that does another operation on the same table. That's causing an Oracle error (mutating tables).