December 2008 - Posts

• For better precision cast decimals before calculations

  I frequently do calculations against decimal values. In some cases casting decimal values to float ASAP, prior to any calculations, yields better accuracy. For example, in the following script both expressions should return 12100.0: SELECT POWER ( POWER Read More... Posted Saturday, December 20, 2008 10:38 PM by Alexander Kuznetsov | 2 Comments

• Great new book for beginners: T-SQL Fundamentals

  I have wanted to have an entry level book on T-SQL for a long time. Instead of explaining some new concept to a junior team member, it would be great to just give a junior programmer a well written entry level book. I have just read the following one: Read More... Posted Friday, December 19, 2008 8:26 PM by Alexander Kuznetsov | 0 Comments

• Stress testing UPSERTs

  Suppose that you need to implement the following logic: IF(row exists) Update the row ELSE Insert a new row. If you already are on 2008, you should use MERGE command, and you don’t need to read this post. Prior to 2008 this logic has to be implemented Read More... Posted Sunday, December 14, 2008 8:30 PM by Alexander Kuznetsov | 8 Comments Filed under: Database Programming, Database Testing, Defensive programming, SQL Server, Transact SQL

• Defensive database programming: fun with UPDATE.

  It is well known that UPDATE ... FROM command does not detect ambiguities. Also it well known that ANSI standard UPDATE may perform very poorly and may be difficult to maintain, because it does not adhere to the fundamental DRY (Don’t Repeat Yourself) Read More... Posted Monday, December 08, 2008 10:56 AM by Alexander Kuznetsov | 14 Comments Filed under: Database Programming, Defensive programming, SQL Server, Transact SQL