查询＆在Firebase中的位置（swift 3）

Question

我如何在Firebase中进行查询？在Oracle SQL查询将

"select * from users where username = "SomeUser" 

我需要做同样的火力地堡，斯威夫特3

Answer 1

您需要使用queryOrderedByChild和queryStartingAtValue。这应该让你开始正确的方向。

let username = "SomeUser" 

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

} 

Answer 2

斯威夫特3 & &火力地堡3

我希望这将有助于你理解。在这里，我们去

这是示例中的数据结构：

这里是代码：

let username = "DavidMouse" 

    // create searchRef or queryRef you name it 
    let searchRef = FIRDatabase.database().reference().child("users").queryOrdered(byChild: "username").queryEqual(toValue: username) 

    // search the username 
    searchRef.observeSingleEvent(of: .value, with: { (snapshot) in 

     guard snapshot.value is NSNull else { 

      // yes we got the user 
      let user = snapshot.value as! String 
      print("\(user) is exists") 
      return 
     } 

     // no there is no user with desire username 
     print("\(username) is exists") 
    }) { (error) in 
     print("Failed to get snapshot", error.localizedDescription) 
    }