private DatabaseReference getDataBase() {
        FirebaseDatabase mDatabase = FirebaseDatabase.getInstance();
        mDatabase.setLogLevel(Logger.Level.DEBUG);
        mDatabase.setPersistenceEnabled(true);
        mDatabase.purgeOutstandingWrites();
        mDatabase.getReference().getRoot().addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
        return mDatabase.getReference();
    }