Using Merge to Update to Insert, Update, and also deleting obsolete records

Question

Hi all!!!
Suppose that a have the following table, called Orders:
ORDERID        STATUS      PRICE
         1          0        100
         2          0        200
         3          0        300
         4          0        350
         5          0        390 Also, there is a procedure that will generate some data on a global temporary table, called Orders_Temp. This temporary table will be used to update the Orders table.+Orders+ have a trigger that will perform different operations when a Insert, Delete or Update command is performed.
Consider that the Orders_Temp table have the following data after running a procedure that is responsible for updating orders data:
ORDERID        STATUS      PRICE
         1          1        100
         2          2        200
         3          0        300
         5          0        390
         6          0        350 As you can see, orders 1 and 2 were updated. Order 3 and 5 were untouched, order 4 was deleted and order 6 was inserted. Merge will handle the correctly handle orders 1, 2, 3, 5 and 6, even though generating a update to orders 3 and 5, that were not changed.
So, here are the questions:
1) How could I delete the order 4 from Orders, since this order was not present on the Orders_Temp? Is there a way to use the merge command to do this?
2) Is there any way to not generate a update operation for orders 3 and 5, that were not changed?
I´m using Oracle 10.2 SE.
Thanks a lot!
Regis

Answer 1

Hello G!
Thank you so much for your help.
Your code took only a modification:
MERGE INTO orders tgt
USING (SELECT A.*, 1 mask
          FROM orders_temp A
        UNION ALL
        SELECT A.*, 0
          FROM orders A
         WHERE NOT EXISTS
                 (SELECT 1
                    FROM orders_temp b
                   WHERE A.order_id = b.order_id)) src
    ON (tgt.order_id = src.order_id)
WHEN MATCHED
THEN
  UPDATE SET tgt.status = src.status, tgt.price = src.price
     /*WHERE src.mask = 1
       AND tgt.status != src.status
       AND tgt.price != src.price*/
  DELETE
     WHERE src.mask = 0
WHEN NOT MATCHED
THEN
  INSERT VALUES (src.order_id, src.status, src.priceWithout doing this, the DELETE WHERE clause was never called. After reading the docs, I found why:
Specify the DELETE where_clause to clean up data in a table while populating or updating it. The only rows affected by this clause are those rows in the destination table that are updated by the merge operation. That is, the DELETE WHERE condition evaluates the updated value, not the original value that was evaluated by the UPDATE SET ... WHERE condition. If a row of the destination table meets the DELETE condition but is not included in the join defined by the ON clause, then it is not deleted. Any delete triggers defined on the target table will be activated for each row deletion.http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_9016.htm
>
From what I understand, if we restrict the records on update set_clause, the delete  where_clause will no be able to process because they were not touched. So, as as workaroud, I´m checking if the record was changed inside my trigger.
Thanks a lot!
Regards.
Regis