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

A note regarding the two solutions that suggest:

1) Insert, if exception then update,

or

2) Update, if sql%rowcount = 0 then insert

The question of whether to insert or update first is also application dependent. Are you expecting more inserts or more updates? The one that is most likely to succeed should go first.

If you pick the wrong one you will get a bunch of unnecessary index reads. Not a huge deal but still something to consider.