iOS - or Query in Firebase

Querying Firebase with Swift 3.0

You need to use queryOrderedByChild to createdAt and than use equalTo Today

let ref = FIRDatabase.database().reference().child("thoughts").queryOrdered(byChild: "createdAt").queryEqual(toValue : "Today")

ref.observe(.value, with:{ (snapshot: FIRDataSnapshot) in
    for snap in snapshot.children {
        print((snap as! FIRDataSnapshot).key)
    }
})

Firebase query in iOS swift

after read firebase documentation, I got my Answer where i made mistake.
here what i was done. i just replace queryEqual instance of child

refhandel = ref.child("SongPlay").queryOrdered(byChild:"post_key").queryEqual(toValue: post_key[myIndex]).observe(.childAdded,   with: { (snapshot) in

if let item = snapshot.value as? [String: AnyObject]{

        let music = MusicDataModel()
        music.setValuesForKeys(item)
        MusicData.append(music)
  }

 })

Query Firebase nested data to check specific value - iOS Swift

When you perform a query, Firebase compares a property of each child node under the location you query to the value you pass in.

I assume that profilesRef points to /profiles in your database. In that case profilesRef.child(user) in your code points to the profile for a specific user already. When you then run a query, you are querying each of the properties of that specific user.

What you like want to do is to get all users with gender equal to Female. In that case you should query the user list:

DatabaseService.shared.profilesRef.queryOrdered(byChild: "gender").queryEqual(toValue: "Female")...

Note that you also should define the index on the level where the query is run, so on /users:

"profiles": {
  ".indexOn": ["gender"]
}

Another alternative (the might scale better) is to not use a query altogether, but instead load the gender property of each individual user in your array. In (approximate) code:

for user in nearbyUserArray {
  DatabaseService.shared.profilesRef.child(user).child( "gender").observeSingleEvent(of: .value) { [weak self] (snapshot) in
    if snapshot.value == "Female" {
      print("snap: \(snapshot)")
    }
  }
}

query & where in Firebase (swift 3)

You need to use queryOrderedByChild and queryStartingAtValue. This should get you started in the right direction.

queryStartingAtValue(username).queryEndingAtValue(username)

let username = "SomeUser"

FIRDatabase.database().reference.child("users").queryOrderedByChild("username").queryStartingAtValue(username).queryEndingAtValue(username).observeEventType(.ChildAdded, withBlock: { (snapshot) -> Void in

}

queryEqual(toValue: username)

let searchRef = FIRDatabase.database().reference().child("users").queryOrdered(byChild: "username").queryEqual(toValue: username)

Firebase query on multiple filters in Swift

The code you show shouldn't event compile. Firebase Database queries can only contain a single orderBy... clause, and can never do suffix matching (your _NCAA is at the end of the key).

To allow you use-case you should have a key/property that consists of the week number, and the org (NCAA/NFL) value. E.g.

Games
    --- 20190220000_NCAA (SportID)
        --- WeekId : 1
        --- WeekOrg : "01_NCAA"
        --- etc...
    --- 20190221000_NCAA
        --- WeekId : 2
        --- WeekOrg : "02_NCAA"
        --- etc...
    --- 20190204000_NFL    
        --- WeekId : 1
        --- WeekOrg : "01_NFL"
        --- etc...
    --- etc...(SportsID)

With this in place you can get the nodes in week 1 for the NCAA with:

gamesRef.queryOrdered(byChild: "WeekOrg").queryEqual(toValue: "01_NCAA").observe(.value, with: { snapshot in

Also see my answer here: http://stackoverflow.com/questions/26700924/query-based-on-multiple-where-clauses-in-firebase

How to make Firebase Database Query to get some of the children using Swift 3?

As El Capitain said, you'll need to use this:

func loadData(){

    let ref = FIRDatabase.database().reference().child("Posts")

    ref?.queryOrdered(byChild: "Des").queryEqual(toValue: "11").observe(.childAdded, with: { snapshot in 
        if let post = snapshot.value as? [String : AnyObject] { 
            // do stuff with 'post' here.

        } 
    })

}

Also, as he mentioned, you'll want to set your security rules to allow you to search by 'Des', or whatever other child node you'll be querying by. In addition, you'll need to set the rules to allow you read access to the query location:

{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null",

    "Posts": {
      "$someID": {
        ".indexOn": ["Des"]
      }
    }
  }
}

However, you're not going to get 'only the images' though, your query will return the entire node. In this case, the query above would return the rrrrrr node.

iOS Firebase -What's the best way to query several levels down? 'InvalidQueryParameter', reason: 'Cannot use multiple queryOrderedBy calls!'

I am going to throw this out as a possible solution.

It's not exactly clear why the current structure is what it is, but I would suggest changing it to

post_comments
   post_id_x
      posted_by: "uid1234"
      comment: "I like pizza"

if the structure needs to stay as is, then simply add this as another node which will make your comment queries much simpler.

Retrieve Data from Firebase using where Query in Swift 4

You need to add a query:

ref.queryOrdered(byChild: "videoid").queryEqual(toValue: "12345").observeSingleEvent(of: .value, with: { snapshot in

more info here:

https://firebase.google.com/docs/reference/swift/firebasedatabase/api/reference/Classes/DatabaseQuery#queryorderedbychild

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