Retrieve count data from Firebase like MySQL

Question

When trying to pull data from a MySQL database, I can do something like:

SELECT * FROM users ORDER BY id WHERE vehicle = car

That should get me all the users that drives a car and not show users that drives a motorcycle for instance.

Is there something like this for Firebase? I can only retrieve specific data from one user?

My firebase database is like this: user -> user info (name, age, vehicle etc..)

I want to query every user that drives a car and display them in a row. How do I do that?

I have tried the following, but I didn't succeed with what I tried to do, since after users the users id is the next child. Is there a way to query past that?

var recents = firebase.database().child('users').orderByChild('department').equalTo(department);
            recents.on('child_added', function(snapshot) {
            var countOfUserInDepartment = snapshot.count;
            
                document.querySelector("#cphCount").innerHTML = countOfUserInDepartment;
            
            });

Frank van Puffelen · Accepted Answer · 2017-09-22 14:43:17Z

2

There are no count queries (nor other aggregation queries) in the Firebase Database. Your options are:

Retrieve all data matching your query and count client-side
Keep a separate count-node that you update whenever you add/remove items.

For #2 you may find it convenient to use Cloud Functions, for which there an an example of keeping such a counter.

Also see:

edited Sep 22, 2017 at 14:43

answered Sep 22, 2017 at 14:40

Frank van Puffelen

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3 Comments

Frank van Puffelen Over a year ago

You use the standard Firebase methods for reading a list of data or querying a list of data.

FeReTu Over a year ago

I have edited my question. How can I query past a child that I "don't know what is"?

Frank van Puffelen Over a year ago

I reopened the question, but have no idea why you mention count in your title. You might want to update that, so that hopefully somebody will be able to help better..

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