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• Let's deprecate UPDATE FROM!

  I guess that many people using UPDATE … FROM on a daily basis do so without being aware that they are violating all SQL standards. All versions of the ANSI SQL standard that I checked agree that an UPDATE statement has three clauses – the UPDATE clause, Read More... Posted Monday, March 10, 2008 2:38 AM by Hugo Kornelis | 30 Comments Filed under: T-SQL, Performance, Best Practices, SQL Server 2008, Standard vs proprietary

• How NOT to pass a lot of parameters

  Did you know that SQL Server allows stored procedures to have up to 2100 parameters? And more important: do you care? Well, some people do care, and Joe Celko seems to be one of them. If you are a regular reader of SQL Server newsgroups, you probably Read More... Posted Thursday, October 04, 2007 10:07 AM by Hugo Kornelis | 15 Comments Filed under: T-SQL, Performance, Best Practices Attachment(s): Sudoku.zip

• What if null if null is null null null is null?

  In this fourth and final part in my series about NULL, I’ll discuss some well-known and some less well-known functions and keywords that are specifically created to deal with NULL values. And I will, of course, explain why null if null is null null null Read More... Posted Sunday, September 30, 2007 11:19 PM by Hugo Kornelis | 9 Comments Filed under: T-SQL, Surprise, Database theory, NULL

• Dr. Unknown, or how I learned to stop worrying and love the NULL

  Two months ago, I posted the first two parts of a series about NULL. After that, I went quiet. Much to do and little time was one excuse. But to be honest, I also lost interest. However, I felt I owe my readers to conclude the series, so I have now forced Read More... Posted Saturday, September 22, 2007 11:35 PM by Hugo Kornelis | 11 Comments Filed under: T-SQL, Database theory, NULL

• The logic of three-valued logic

  In my previous post , I explained what NULL does and does not mean, how and why the rule of NULL propagation forces any expression involving NULL to result in NULL. I also mentioned that comparisons involving NULL do not result in NULL but, rather, in Read More... Posted Tuesday, July 17, 2007 11:58 PM by Hugo Kornelis | 8 Comments Filed under: T-SQL, Database theory, NULL

• NULL - The database's black hole

  I once read a scientific article on black holes that started of on the observation that, since a hole is the absence of anything and black is invisible in space, a black hole is in fact an invisible nothing – so what the heck are we talking about? Well, Read More... Posted Friday, July 06, 2007 12:20 AM by Hugo Kornelis | 25 Comments Filed under: T-SQL, Database theory, NULL

• The Beatles versus the Stones - the explanation

  On December 31 of last year, I posted this brain teaser , promising to post the answer “in a few days”. Apparently, 15 is a few J . In case you have forgotten what the puzzle was about and are too lazy to click the link above, the bottom line is that Read More... Posted Tuesday, January 16, 2007 10:44 PM by Hugo Kornelis | 0 Comments Filed under: T-SQL, Surprise, Internals, Indexing

• The Beatles versus the Stones

  Here’s a nice brain teaser, just before the end of the year. Despite the title, it is related to SQL Server, not to music! A common misconception amongst SQL Server users is that a clustered index on a table will ensure that data is returned in the order Read More... Posted Sunday, December 31, 2006 1:49 PM by Hugo Kornelis | 19 Comments Filed under: T-SQL, Surprise, Internals, Indexing

• Just stuff it!

  I’m sure you’ve all heard it, and probably even said it, many times: “SQL Server sucks at string manipulation”. And with good reason – it is true. But not quite as true as many seem to believe. I notice that many people who complain about SQL Server lacking Read More... Posted Thursday, October 12, 2006 8:50 PM by Hugo Kornelis | 12 Comments Filed under: T-SQL, Tricks

• The prime number challenge – great waste of time!

  No sane person would even consider using SQL Server to construct a list of prime numbers. So just to prove that I’m not sane (as if there could be any doubt!), this post will be about finding prime numbers. First a bit of history. Ward Pond wrote about Read More... Posted Saturday, September 23, 2006 10:54 PM by Hugo Kornelis | 10 Comments Filed under: T-SQL, Tricks, Prime number challenge, Performance

• Fun with ambiguous table names

  Earlier today, I realised that Microsoft has forgotten to include some keywords in the list of reserved keywords. Now, a wise developer will still take care to omit those names when naming tables – but a bored developer can have loads of fun exploring Read More... Posted Saturday, September 02, 2006 9:24 PM by Hugo Kornelis | 1 Comments Filed under: T-SQL, Surprise

• Relating unrelated rows

  A recurring question in the newsgroups is: “How do I output unrelated rows side by side?” I’ll use the AdventureWorks database as an example. Suppose that my manager wants a report listing, for each order, all products ordered and all reasons the customer Read More... Posted Friday, July 14, 2006 10:23 PM by Hugo Kornelis | 3 Comments Filed under: T-SQL, Tricks, Performance