PHP scripts JSON android login

database: mobiledb
table androidlogin
columns - id,user,pass
<?php

//Create fields for database , server , username ,password, database
$dbhost = "localhost";
$dbuser = "root";
$dbpass = "";
$dbdb = "mobiledb";

//Connect to mySQL
$connect = mysql_connect($dbhost , $dbuser , $dbpass)
or die("connection error");

//select the database
mysql_select_db($dbdb)or die("database selection error");

//retrieve the login details via post
$username = $_POST['username'];
$password = $_POST['password'];

//query the table android login
$query  = mysql_query("SELECT * FROM androidlogin WHERE user = '$username' AND

pass = '$password'");

//check if there is any results returned
$num = mysql_num_row($query);

//if a record was found matching the details entered in the query
if($num==1)
{
//create a while loop that places the returned data into an array
while($list = mysql_fetch_assoc($query))
{
//store the returned data into variable
$output = $list;

//encode the data in JSON format
echo json_encode($output);
}

//close the connection
mysql_close();

}
?>

or 

<?php

//Create fields for database , server , username ,password, database

$dbhost = "localhost";

$dbuser = "root";

$dbpass = "";

$dbdb = "mobiledb";

//Connect to mySQL

$connect = mysql_connect($dbhost , $dbuser , $dbpass)

or die("connection error");

//select the database

mysql_select_db($dbdb)or die("database selection error");

//retrieve the login details via post

$username = $_POST['username'];

$password = $_POST['password'];

//query the table android login

$query  = mysql_query("SELECT * FROM androidlogin WHERE user = '$username' AND pass = '$password'");

//create a while loop that places the returned data into an array

while($list = mysql_fetch_assoc($query))

{

//store the returned data into variable

$output[] = $list;

//encode the data in JSON format

echo json_encode($output);

}

//close the connection

mysql_close($connect);

?>