This topic itself is nice and the techniques mentioned in this article can be used in many occasions.

However "change a dimension ID to see what happens" section does not cover the situation when the staging fact table already has a transaction (record) with same sale person id , product id and date.

The following update statement will create a record with a duplicate key (100, 1004, 20101102), if allowed.

UPDATE staging.SalesDetailSource

SET SalesPersonID = 100

WHERE ProductID = 1004

AND SalesPersonID = 101

AND SaleDate = 20101102;

Any explanation on how to handle this situation will be interesting.

Thanks.