It is tightly integrated into the entire Microsoft development toolchain. There are free versions given to developers. And then there's the persistent myth of "

It is tightly integrated into the entire Microsoft development toolchain. There are free versions given to developers. And then there's the persistent myth of "Nobody ever got fired for buying Microsoft". They used to say that about IBM. They don't anymore. A lot of it is inertia, as well. People who have been writing software for MS SQL server for the past couple of decades probably aren't going to change any time soon. Plus with MS Azure, MS SQL server is easy for a non DBA to setup, add failover and scale.