OK, let me explain...

The script I posted is just an example(my real example is different and much more complex,but this doesn't matter), what I need to understand is why when...

The business key is the FirstName. I am merging the initial table with update tables and I am doing this based on the FirstName(which will not chanege in my case,...

Here the script

CREATE TABLE Persons

(

ID int IDENTITY PRIMARY KEY

,FirstName varchar(20)

,LastName varchar (20)

,Title varchar(10)

,IsRowCurrent tinyint

,LastUpdated DATE

,ValidFrom DATE

,ValidTo DATE

)

--Populate Persons table with existing customers

INSERT INTO Persons

VALUES ('Anna','Kournikova','Miss',1,'2012-11-01','2012-11-01','9999-12-31')

...