title: How to design Firebase database for Booking app?
body: <p>I am new to databases. In learning purposes I'm creating a simple booking app (with React-Redux) that would have tennis courts to book. First, you choose day and time, then you can see the exact courts (the courts are different) available for that date and time. </p>
  
  <p>I was reading docs in Firebase and answers to similar questions in SO but I'm still confused. 
  Could you tell me, how can I structure my Firebase database and query only available courts for each date and time, or at least, what should I study to be able to make it by myself?</p>