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

From http://www.praetoriate.com/oracle_tips_upserts.htm:

"In Oracle9i, an UPSERT can accomplish this task in a single statement:"

INSERT
FIRST WHEN
   credit_limit >=100000
THEN INTO
   rich_customers
VALUES(cust_id,cust_credit_limit)
   INTO customers
ELSE
   INTO customers SELECT * FROM new_customers;