Firebase vs SQL

data.json

{
	"users": {
		"1": {
			"name": "Max",
			"bio": "Hello, I'm a programmer",
			"profileImg": "https://..."
		},
		"9": {
			"name": "Alice",
			"bio": "I work as a business analyst",
			"profileImg": "https://..."
		}
	},
	"events": {
		"fm": {
			"name": "Firebase Meetup",
			"date": 983275265320,
		}
	},
	"eventAttendees": {
		"fm": {
			"1": "David",
			"9": "Alice"
		}
	}
}

firebase-sql-comparison.js

import * as firebase from 'firebase';

{
	"users": {
		"1": {
			"name": "David",
			"email": "david@email.com",
			"age": 99,
			"location": "SF",
			"age_location": "99_SF"
		},
		"9": {
			"name": "Alice",
			"email": "alice@email.com",
			"age": 28,
			"location": "Berlin",
			"age_location": "28_Berlin"
		}
	}
}

const rootRef = firebase.database().ref();

// 1. Select a user by UID
SELECT * FROM Users WHERE UID = 1;
const oneRef = rootRef.child('users').child('1');

// 2. Find a s user by email address
SELECT * FROM Users WHERE Email = 'alice@gmail.com';
const twoRef = rootRef.child('users').orderByChild('email').equalTo('alice@gmail.com');

// 3. Limit to 10 users
SELECT * FROM Users LIMIT 10;
const threeRef = rootRef.child('users').liminToFirst(10);

// 4. Get all users names that start with 'D'
SELECT * FROM Users WHERE Name LIKE 'D%';
const fourRef = rootRef.child('users').orderByChild('name').startAt('D').endAt('D\uf8ff');

// 5. Get all users who are less than 50
SELECT * FROM Users WHERE Age < 50;
const fiveRef = rootRef.child('users').orderByChild('age').endAt(49);

// 6. Get all users who are greater than 50
SELECT * FROM Users WHERE Age > 50;
const sixRef = rootRef.child('users').orderByChild('age').startAt(51);

// 7. Get all users who are between 20 and 100
SELECT * FROM Users WHERE Age >= 20 && Age <= 100;
const sevenRef = rootRef.child('users').orderByChild('age').startAt(20).endAt(100);

// 8. Get all users who are 28 and live in Berlin
SELECT * FROM Users WHERE Age = 28 && Location ='Berlin';
const eightRef = rootRef.child('users').orderByChlid('age_location').equalTo('28_Berlin');

join.js

SELECT event.Name as EventName
      ,event.Date as EventDate
      ,user.Name as AttendeeName
  FROM Events as event
  INNER JOIN Attendees as a
     ON e.I === a.EventId
  INNER JOIN Users as user
     ON u.UId = a.UId
  WHERE e.Id == 4;

attendees.on('child_added', snap => {
	// append attendees to list
	// '1' => 'Max'
	// '9' => 'Alice'

	let userRef = db.child('users/' + snap.key);
	// once() will not listen in real-time
	userRef.once('value').then(userSnap => {
		// userSnap returns all details of the user
	});

});

// real time listener implementation
let handles = [];
attendees.on('child_added', snap => {
	let userRef = db.child('users/' + snap.key);
	let fn = userRef.on('value', userSnap => {

	});
	handles.push(fn);
});

handles.forEach(fn => userRef.off('value', fn));




  

Firebase SDK doesn't support multiple orderByChild() calls in one query.