将mysql查询转换为firebase数据库

有人知道如何将这个mysql查询转换为firebase数据库queryAndroid吗

SELECT * FROM chat_info
WHERE receiver = '$sender' 
    and sender= '$receiver' 
UNION 
    SELECT * 
    FROM chat_info 
    WHERE sender='$sender' 
        and receiver='$receiver' 
ORDER BY sno 
DESC

从未编写过任何Android应用程序，但以下是文档和示例：

---

需要看到你的Firebase结构，如文本请，没有图像或链接。另外，请复习并复习

compile 'com.google.firebase:firebase-database:10.2.6' // put this inside the 'build.gradle'-file

// Configure your database-rules =>

// Read from database and sort =>

private DatabaseReference mDatabase;
// ...
mDatabase = FirebaseDatabase.getInstance().getReference();

// My top posts by number of stars
String myUserId = getUid();
Query myTopPostsQuery = databaseReference.child("user-posts").child(myUserId)
        .orderByChild("starCount");
myTopPostsQuery.addChildEventListener(new ChildEventListener() {
    // TODO: implement the ChildEventListener methods as documented above
    // ...
});

// All examples are copied from firebase.google.com/docs