mysql oracle postgresql

postgreSQL mysql oracle differences

I’m having to start building the architecture for a database project but i really don’t know the differences between the engines.

Anyone can explain whats the pros and bads of each of these three engines? We’ll have to choose one of them and the only thing I actually know about them is this:

  • Mysql & Postgres:

    • Are free but not so good as oracle
    • Mysql as security problems (is this true?)
  • Oracle:

    • Best data base engine in the world
    • Expensive

Can someone clear out other differences between them? This is a medium/large (we’re thinking of around some 100 to 200 tables) project with low budget, what would you choose? And with a higher budget?