Sql Server 2008 MERGE - best way to get counts

Question

I'm wondering what y'alls would recommend as the best way to go about getting the action counts from a MERGE statement in Sql Server.

So, i.e. I run a MERGE which does some inserts, some updates and some deletes, ... I would like to be able to find out HOW MANY inserts, HOW MANY updates and How Many deletes.

What'd be the best way to do this?

Answer 1

You could specify an OUTPUT clause on your MERGE statement and get an output report of what's been done during MERGE.

MERGE (targetTable) AS t 
USING (sourceTable) AS s
ON t.ID = s.ID
WHEN MATCHED THEN
  (some statements)
WHEN NOT MATCHED THEN
  (some statements)
OUTPUT
  $action, inserted.ID 'inserted', deleted.ID 'deleted'
;

This will give you a row for each "action" (insert, update, delete) for each operation. If it's a lot of statements, you could also OUTPUT INTO @tableVar and then look at the table variable.

DECLARE @tableVar TABLE (MergeAction VARCHAR(20), InsertedID INT, DeletedID INT)

MERGE (targetTable) AS t 
USING (sourceTable) AS s
ON t.ID = s.ID
WHEN MATCHED THEN
      (some statements)
WHEN NOT MATCHED THEN
      (some statements)
OUTPUT
      $action, inserted.ID 'inserted', deleted.ID 'deleted' INTO @tableVar
;

SELECT MergeAction, COUNT(*) 
FROM @tableVar  
GROUP BY MergeAction

Check out the Books Online for details on the MERGE statement and the OUTPUT clause.

Marc