有没有一种方法可以使用“ join”查询从Firebase数据库中检索Android中的数据？

Question

我尝试在Firebase中执行联接查询，但是代码未返回任何内容。场景是我需要在牌照后面找到要搜索的用户phoneNumber。我尝试了以下方法，但没有成功。 我从数据库中附加了代码和json文件。 谢谢

我正在尝试此解决方案，但没有成功How to perform join query in Firebase?

databaseReference.child("cars").child("User"+text.toUpperCase()).orderByChild("licenceNumber").equalTo(text.toUpperCase()).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                for(DataSnapshot postSnapshot : dataSnapshot.getChildren())
                {
                    final Car carNumber = postSnapshot.getValue(Car.class);
                    String UID = carNumber.getId();

                    databaseReference.child("Users").child(UID).addListenerForSingleValueEvent(new ValueEventListener() {
                        @Override
                        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                            for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                                final User user = postSnapshot.getValue(User.class);
                                String phone = user.getPhoneNumber();
                                textView2.setText(phone);
                            }
                        }

                        @Override
                        public void onCancelled(@NonNull DatabaseError databaseError) {

                        }
                    });
                }
            }
            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

{
  "Users" : {
    "1HvAKvh9AETSFYMTqbOIq6AlKap2" : {
      "email" : "bb@ll.com",
      "name" : "John",
      "phoneNumber" : "1111"
    },
    "8RxAsvjDMhTugZtbm8etoxcJ6Ts1" : {
      "email" : "nnn@gmail.com",
      "name" : "Jane  Doe",
      "phoneNumber" : "123456789"
    },
    "MuM99wZYuhbpbXxcv3wXxy9IGqh2" : {
      "email" : "Fff@mail.com",
      "id" : "MuM99wZYuhbpbXxcv3wXxy9IGqh2",
      "name" : "Violeta",
      "phoneNumber" : "1234"
    },
    "Np1jymmdVpMi3hqKDrTPdYuSR9g2" : {
      "email" : "ddd@fff.com",
      "id" : "Np1jymmdVpMi3hqKDrTPdYuSR9g2",
      "name" : "Henry",
      "phoneNumber" : "12345"
    },
    "PFalUadu8xf46siLWikQLLeK7L92" : {
      "email" : "Hjjj@hhhh.com",
      "id" : "PFalUadu8xf46siLWikQLLeK7L92",
      "name" : "George",
      "phoneNumber" : "077292"
    }
  },
  "cars" : {
    "1HvAKvh9AETSFYMTqbOIq6AlKap2" : {
      "UserAR99KTA" : {
        "id" : "1HvAKvh9AETSFYMTqbOIq6AlKap2",
        "licenceNumber" : "AR99KTA"
      }
    },
    "8RxAsvjDMhTugZtbm8etoxcJ6Ts1" : {
      "UserGG77HHH" : {
        "id" : "8RxAsvjDMhTugZtbm8etoxcJ6Ts1",
        "licenceNumber" : "GG77HHH"
      },
      "UserHHHVVFF" : {
        "id" : "8RxAsvjDMhTugZtbm8etoxcJ6Ts1",
        "licenceNumber" : "HHHVVFF"
      },
      "UserSV07WNE" : {
        "id" : "8RxAsvjDMhTugZtbm8etoxcJ6Ts1",
        "licenceNumber" : "UU07WUE"
      }
    }
  }
}