SQL Query to Firebase query

Question

The SQL query that I want to apply is:

SELECT time FROM Appointment WHERE date = "3/15/2019" AND time = "9:00AM"

but I don't know how to translate it in Firebase. I am using Firebase in Android Studio. My goal here is to prevent date and time duplicate since the app that I'm developing is an online appointment.

Database:

Appointment
    angelcrist
        aptype: "Objective(Computerized)"
        date: "3/15/2019"
        name: "Hephep Horray"
        time: "9:00AM"
    miriammejia
        aptype: "Objective(Computerized)"
        date: "3/5/2019"
        name: "Romz Ysmael"
        time: "9:00AM"

Possible duplicate of [Query based on multiple where clauses in Firebase](https://stackoverflow.com/questions/26700924/query-based-on-multiple-where-clauses-in-firebase) — André Kool, Mar 08 '19 at 17:11

Alex Mamo · Answer 1 · 2019-03-08T15:41:18.990

2

There is no way you can do this with the Firebase realtime database. It does not have the capability to perform filtering on multiple conditions. If you have a SQL background, I can say that there are no "multiple where clauses" in Firebase. If you want to check for matches on multiple properties, you'll have to create a composite field as explained in my answer from the following post:

How to sort Firebase records by two fields (Android)

If you consider at some point to try using Cloud Firestore, please note it allows you to filter on multiple conditions. Chaning multiple whereTo calls are working perfectly fine.

edited Mar 08 '19 at 15:41

answered Mar 08 '19 at 12:52

Alex Mamo

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oh..That's what I'm thinking too; the query limitations of firebase. But anyway, thanks. I will try the Cloud Firestore.. – Romz Ysmael Mar 08 '19 at 14:27
You're welcome! I also recommend you to try Cloud Firestore. – Alex Mamo Mar 08 '19 at 14:46

score 0 · Answer 2 · answered Mar 08 '19 at 08:31

First fetch your Appointment data for that particular date using below query, and loop through dataSnapshot childrens to check if you have the time available for that date.

reference.orderByChild('date').equalTo("<yourDate>")
.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for(DataSnapshot snap: dataSnapshot.getChildren()) {
               //Check for time here
            }
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
});

I did that already. The problem is, it gets all the values of time. But I'll still try it again. Thanks! — Romz Ysmael, Mar 08 '19 at 14:26

SQL Query to Firebase query

2 Answers2