I tested GUID column and run into perfromance problems for this exact reason to return the unique value for application that generates a service requests . My solution was to...

more elegant and better performing COALESCE solution

firstname = COALESCE(@firstname,firstname)

and

lastname= COALESCE(@lastname,lasttname)

.. and one more comment

dynamic SQL is always has to be a last and least favorite choice

because it is...

Excellent article! Ready to use to mentor development team!

Great elegant use of Conditional Split in Incremental loads

Have you compared the performance of this method with more traditional checksum method. The...

There are great side books on Amazon for this all from impressive authors

This item: SQL Server 2008 Query Performance Tuning Distilled (Expert's Voice in SQL Server) by Grant Fritchey

Microsoft...

Run DBCC FREEPROCCACHE when you want to clear all execution plans from the cach.

http://www.sqlmag.com/Article/ArticleID/47502/Using_Dynamic_Filters_in_Queries.html

You got to clear the procedure cach every time if you do repeatable executions. Run DBCC FREEPROCCACHE when you want to clear all execution plans from the cach. There...

"TOP" versus "SELECT 1" performance varies depending on many factors . One of them is then "where" clause is in query and it is the most frequent usage of TOP...