Guest Columnist: Jeff Moden

He admits it wasn't his idea but his head sure wishes it was. SQL Server MVP Jeff Moden explains a wonderful, super simple, very high performance formula that will calculate ISO Week Numbers. If you're "stuck" with SQL Server 2005 or less, you're going to like this a whole lot!  Read more...

In this sequel to his first "Hierarchies on Steroids" article, SQL Server MVP Jeff Moden shows us how to build a pre-aggregated table that will answer most of the questions that you could ask of a typical hierarchy. Any bets on whether Santa is packin’ a Tally Table in his bag or not?  Read more...

SQL Server MVP Jeff Moden shows us a new very high performance method to convert an "Adjacency List" to “Nested Sets” on a million node hierarchy in less than a minute and 100,000 nodes in just seconds. Not surprisingly, the "steroids" come in a bottle labeled "Tally Table".  Read more...

It's a well known fact that Scalar UDFs are the stuff of performance nightmares in T-SQL. But are they really as bad as they say? SQL Server MVP Jeff Moden shows us that they might not really be as big a problem as you might think and what you can do when they actually are.  Read more...

Part two of this fantastic series from Jeff Moden looks at generating date data, something which can be handy for any number of testing purposes.  Read more...

A simple problem that can become complex in T-SQL. How do you find the rows that match 2 conditions, but not a third, in an efficient manner. MVP Jeff Moden gives us a solution.  Read more...

Learn how you can easily generate large amounts of test data efficiently in this new series from Jeff Moden. Part 1 covers integers and floating point values.  Read more...

"Counting" is essential to many high performance code techniques. SQL Server MVP, Jeff Moden, shows us how to make sure that we're "Counting" and not "Crippling" our trick-code.  Read more...

The Tally Table has proven to be a simple and elegant method for avoiding many varieties of RBAR. Unfortunately, one of its more common uses, that of a CSV splitter, has a well-known and serious performance problem. MVP Jeff Moden shows us what that problem is and how to correct it. (UPDATED with additional info and attachments on 5/12/2011).  Read more...

Learn how you can query a hierarchy of data and also return the results in an ordered fashion. A handy T-SQL skill that you will use over and over again.  Read more...

SQL Server MVP Jeff Moden shows us a quick and dirty bit of SQL Spackle to display the content of VARCHAR(MAX) and NVARCHAR(MAX).  Read more...

Another in the series of articles to help you "fill in the cracks" in your T-SQL knowledge. MVP Jeff Moden shows us a super simple, high performance method to solve this timeless problem.  Read more...

Fill in another bit of your T-SQL knowledge about STR(). It right justifies, rounds, and controls the output width of columns. Sounds perfect but here's why you might not want to use it.  Read more...

Fill in another bit of your T-SQL knowledge by learning how to quickly group ranges of contiguous dates without RBAR.  Read more...

Another in our series of articles to help you fill in the cracks in your knowledge with SQL Spackle. MVP Jeff Moden shows us how IsNumeric works and how you should use it.  Read more...

Fill in another bit of your T-SQL knowledge by learning how to sort a result set by the proper month order, but use the month name instead.  Read more...

A review of MVP Grant Fritchey's "Dissecting Execution Plans". This is one book that you'll want on your bookshelf.  Read more...

For today's Friday poll we have a guest editorial from Jeff Moden. The head of the anti-RBAR alliance has spent a lot of time trying to help others write better T-SQL and solve their problems with code that performs well. However this Friday Jeff asks about the CLR and how you are using it, or not using it, in the real world.  Read more...

Revisiting his very popular article on the running total and ordinal rank problems, MVP Jeff Moden brings us a detailed analysis of how you might want to implement a solution in T-SQL.  Read more...

Replacing multiple spaces with a single space is an old problem that people use loops, functions, and/or Tally tables for. Here's a set based method from MVP Jeff Moden.  Read more...