按2个键对FireBase中的数据进行排序

firebase.database().ref('users').orderByChild('age').once('value')
  .then(function(snapshot) {
    snapshot.forEach(function(childSnapshot) {
      var childKey = childSnapshot.key;
      var childData = childSnapshot.val();
      // 处理排序后的数据
    });
  });

firebase.database().ref('users').orderByKey().once('value')
  .then(function(snapshot) {
    snapshot.forEach(function(childSnapshot) {
      var childKey = childSnapshot.key;
      var childData = childSnapshot.val();
      // 处理排序后的数据
    });
  });

firebase.database().ref('users').orderByValue().once('value')
  .then(function(snapshot) {
    snapshot.forEach(function(childSnapshot) {
      var childKey = childSnapshot.key;
      var childData = childSnapshot.val();
      // 处理排序后的数据
    });
  });

firebase.database().ref('users').orderByPriority().once('value')
  .then(function(snapshot) {
    snapshot.forEach(function(childSnapshot) {
      var childKey = childSnapshot.key;
      var childData = childSnapshot.val();
      // 处理排序后的数据
    });
  });