One of biggest the factors that decides which technology is used in the application stack is the cost of acquisition. I've seen many application architectures drawn on a whiteboard where the technical team was embarrassed to show them, but they justified the design by trying to keep software licensing costs down. When it comes to the database environment, the usual suspects are Oracle, SQL Server, MySQL, and PostgreSQL. Oracle, the dominant player in the database space, is also the most costly. At the low end, Oracle does have reasonably priced offerings and even a free Express Edition, but they are limited. Most people have needs beyond the low-priced offerings and fall into the enterprise sales machine of Oracle. This usually results in a high-price quote that makes your CFO fall out of his/her chair, and you're back to designing your solution in order to keep your licensing costs down.

Then comes Microsoft SQL Server. This is your first reasonably viable option. The...