How to use merge instead of slowly changing dimension

Performs insert, update, or delete operations on a target table based on the results of a join with a source table.

MERGE INTO dbo.productdata AS target

USING dbo.staging_productdata AS source

   ON target.ProductNumber = source.ProductNumber

   AND target.DateTime = source.DateTime

WHEN MATCHED THEN

   UPDATE SET target.product = source.product

WHEN NOT MATCHED BY TARGET THEN

   INSERT (ProductNumber, DateTime, product)

   VALUES (source.ProductNumber, source.DateTime, source.product)

--With delete

MERGE INTO dbo.productdata AS target

USING dbo.staging_productdata AS source

   ON target.ProductNumber = source.ProductNumber

   AND target.DateTime = source.DateTime

WHEN MATCHED THEN

   UPDATE SET target.product = source.product

WHEN NOT MATCHED BY TARGET THEN

   INSERT (ProductNumber, DateTime, product)

   VALUES (source.ProductNumber, source.DateTime, source.product)

WHEN NOT MATCHED BY SOURCE THEN

   DELETE

Cheers!
Uma