I’ll admit, I haven’t used the DB_NAME very often. I pretty much use it in a single scenario. With all of my projects I use Continuous Deployment or Continuous Integration, whatever your choice of word is. When doing CI I have automatic deployment of any database scripts that need to run as I deploy to each environment: local, development, production, etc.
On occasion, a script needs to apply a custom value for each environment like a user ID. To accomplish I use DB_NAME to perform a case statement as follows.