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JOIN types and performance
There are basically three main types of joins in SQL Server, each one of which has its own characteristics, advantages and drawbacks. You’ll find these three operators in query plans. Knowing how...
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How to create, find and eliminate deadlocks
Deadlocks are typically encountered in high-load scenarios or in complex concurrent transactions. And the worst part is, you probably won’t see them until you’re live in production. Luckily, finding...
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Web requests using a CLR procedure
For most things that you can’t do straigh-off in T-SQL, you have the option to write a Common Language Runtime procedure. This gives you access to a huge array of APIs, so you can create really cool...
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Decrypting SQL objects
Ever wished you could decrypt a database object in SQL Server? The good news is, you can, even in newer versions of SQL Server! This article will take you through the basics of how to decrypt a...
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Using Service Broker to send messages
Until now, I’ve never really looked any closer at Service Broker and message queues in SQL Server, but it turns out it’s a really useful feature if you need asynchronous processing or any other kind of...
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Converting JSON data to XML using a T-SQL function
Depending on your line of work, you may some time stumble over JSON data. JSON is a data format specifically designed to work well with Javascripts on web pages, so it’s fairly common in web service...
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Kerberos Configuration Manager for SQL Server
Don’t you just hate it when you once again have to look to Google for help on fixing some obscure Kerberos related authentication problem on SQL Server? Luckily, I found a blog post about fixing...
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Isolation levels
Isolation levels affect how aggressively SQL Server places and holds locks on tables and schemas. Get too lazy and you’ll end up with phantom data and dirty reads. Be too zealous, and you’ll end up...
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Using DDL triggers to set up version control
DDL triggers allow you to write SQL code that executes whenever a DDL (data definition language) event occurs. This means you can capture, and handle, any event that modifies for instance stored...
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A function to calculate recurring dates
When you’re using Microsoft Outlook, or pretty much any other personal information manager, you can create calendar appointments that are “recurring”, i.e. you can have them repeat at a defined...
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Cool MERGE features you may not know about
The MERGE statement is a really powerful way to create what’s called “upserts”. In this article, I’ll take a more detailed look at how you can make the best use of MERGE and I’ll also show you some...
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Great article series on statistics
I took some time today to read up on Dale Burnett’s series on statistics in SQL Server. In seven detailed posts, Dale goes through different aspects of how statistics work in SQL Server, and how to use...
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Shrinking tempdb without restarting SQL Server
Ok, so even if you’re a seasoned veteran T-SQL coder, at some time you will write a query that runs away and supersizes the tempdb database. This, in turn, might fill up your disk and cause other...
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Slowly changing dimensions (part 3)
In the third installment of the series on slowly changing dimensions, we’re going to tackle the question of how to manage accumulated fact aggregates in a solution that uses SCD 2 dimensions. While SCD...
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Execution order of non-deterministic functions
Here’s a strange insight that I gained when building a test case where I needed some randomized values. In order to generate random values, you can use the NEWID() function, which creates a...
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Analyzing partition usage and skewing
I sometimes want to know how my data is spread across different partitions in a table or index – after all, this can affect performance and storage a great deal, and if the data is really badly skewed,...
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About the spool operator
The spool operator is one of those icons that will show up in a query plan now and then. In this post, we’ll take a closer look at what it does in a query plan, how it affects performance, and what you...
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Calculating business days and holidays
A common scenario you may have encountered is the need to calculate the first business day after a given date. There are quite a few ugly ways to solve this, including cursors, but there are also some...
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Aggregate string concatenations
A common reporting scenario is that your report has to concatenate an aggregate of string values from rows. Many other database platforms even have built-in aggregate functions that will concatenate...
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Parsing parenthesis expressions
Today’s post illustrates a pretty cool application of SQL Server’s built-in XML and XQuery support, used to parse parenthesis-delimited expressions. You may want to get your reading glasses on for this...
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