you pick "something" based on the requirements of the application or whatever solution you're building. if your requirements mention that you need to have multiple people accessing the database at the same time, RDBMS environments like MySQL, Postgres, Oracle would be appropriate. If it is a single application instance with no multi-user access, SQLite might be appropriate. However, if you're choosing SQLite, FileMaker, FoxPro, MS Access, etc and your requirements specify that you needed multi-user access, then you've made a large mistake.