Mongodb连接错误？

<?php
$username='root';
$password='xyz';
$database='abc';
$host='localhost';
function MongoConnect($username, $password, $database, $host) {
    $con = new Mongo("mongodb://{$username}:{$password}@{$host}"); // Connect to Mongo Server
    $db = $con->selectDB($database); // Connect to Database
}
$collection=$db->movie;
$document = array( "name" =>"Calvin and Hobbes");
$collection->insert($document);
// find everything in the collection
$cursor = $collection->find();
// iterate through the results
foreach ($cursor as $document) {
    echo $document["name"] . "
";
}
?>

I had installed MONGO DB and tried to test my DB, but I am getting an ERROR

"Internal Server Error 500"

And also my Test.php file have my own content called Hello World, but if I had run the TEST.php file it displays Nothing. My DB table is not accessing and I wasn't able to retrieve data from my Database. So Kindly help me out here.

There can be several things wrong.
First - is Mongo driver installed?
Second - your MongoConnect function have no effect. You are defining it and not calling. Plus even if you would call it there would be no effect as $db is only in function scope and not outside. Third - because function MongoConnect have no effect "$collection=$db->movie;" will result in problem as $db is not defined.
Consult http://php.net/manual/en/mongocollection.insert.php on how to insert data in collection.

Internal Server Error only occured when misspelled in code or some of function called wrongly. Please review ur code.