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 cool tricks I picked up along the way.
Category: Advanced
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 frequency. This, however may not only apply to your project meeting appointments, but also to some database solution. I decided to give it a go at building a table value function that returns a list of dates, based on a given set of parameters.
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 procedures, views, DML trigger, etc. In this post, I’m going to set up a simple version control process using DDL triggers.
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 troubleshooting deadlocks. Here’s an overview of the different types of isolation levels available, to help you choose which one is best for you.
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 Kerberos problems using a new tool from Microsoft, the Kerberos Configuration Manager for SQL Server. This tool will go through your settings and SPNs and what-not, to help you resolve the problem.
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 applications. If you’ve managed to land JSON data on your server and need to convert it to XML, here’s an idea how to.
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 queued messaging logic. Messages can be sent within a database, a server, or even between servers.
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 database object, and it will hopefully give you some deeper knowledge of how encrypted objects are stored in the database, and how to access them.
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 stuff, way beyond what T-SQL would normally allow you to do. Here, we’ll explore how to write a web request procedure in C#, so you can download a web document (for instance, a file on a REST service) directly into a table or a string variable using just a regular function call.
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 and solving deadlock issues isn’t as complicated as it may sound. All it takes is a bit of logging and patience, along with some basic know-how of how locking mechanisms work in SQL Server.