MERGE question

[djj55]

Hello, SQL 2008R2
I was looking at the MERGE command with respect to a process I am currently using. I thought the INSERT/UPDATE done by MERGE would speed things up.

Problem: Currently during the update a field is updated in target that indicates date of change for one column. Can this be done with a merge?

UPDATE target
SET ....
-- various columns updated then
  , myColumn = #Changes.myColumn
  , myColumnChanged = 
    CASE 
-- old value not equal to new value or no old value but have a new value
      WHEN target.myColumn <> #Changes.myColumn OR 
        (target.myColumn IS NULL AND #Changes.myColumn IS NOT NULL) 
      THEN CAST(GETDATE() AS DATE) 
    ELSE myColumnChanged 
    END
FROM target 
INNER JOIN #Changes  
    ON target.PKvalue = #Changes.PKvalue

Note that the current process works so I do not need to change it but would like to know if it is possible to do the update within the MERGE or do I need to use OUTPUT and do a second update.
Thank you,

djj
The Lord is my shepherd (Psalm 23) - I need someone to lead me!

 

[markros]

It seems to me you should be able to either use two different MATCHED conditions or just use update with case statement similar way.

PluralSight Learning Library

 

[djj55]

Thank you markros. I entered MATCHED for BOL search and found "Inserting, Updating, and Deleting Data by Using MERGE" which covers MATCHED, which may work.

As stated this is just a learning exercise which you helped along.

Thanks again,

djj
The Lord is my shepherd (Psalm 23) - I need someone to lead me!