Checking if a particular value exists in the Firebase database

Question

I am making an Android application using Firebase realtime database. When a new user registers on my app, that user\'s data is saved in the Firebase database. <

Answer 1

Try this:

DatabaseReference ref=FirebaseDatabase.getInstance().getReference().child("Users");
ref.orderByChild("username").equalTo(Nick123).addValueEventListener(new ValueEventListener(){
  @Override
  public void onDataChange(DataSnapshot dataSnapshot){
      if(dataSnapshot.exist() {
         //username exist
          }
        }

You have to use orderbychild and equalto to check the value if it is there. If you dont use orderbychild and equalto then it will just check if username child node is there and doesnt care about the value.

this orderByChild("username").equalTo(Nick123) is like saying:

WHERE username=Nick123