phpproblem

<!Doctype html>
<html>
<head>
  <meta charset="utf-8"><!--characters recognised-->
  <title>Register</title>
<style>

body{
  background-image: url(my_images//background_homepage.jpg);
  background-repeat: no-repeat;
  background-size:cover;
}
</style>
</head>
<body>

<?php
  extract( $_POST );//superglobal variable

if( isset($_POST['submit'] ) ) {

  print_r($_POST);

  //Getting the variables from 'registerForm' ++  /* checking if user inputs are set */
  $first_name = (isset($_POST['onoma'])) ? $_POST['onoma'] : NULL;
  $last_name = (isset($_POST['epwnumo'])) ? $_POST['epwnumo'] : NULL;
  $age = (isset($_POST['hlikia'])) ? $_POST['hlikia'] : NULL;
  $job = (isset($_POST['epaggelma'])) ? $_POST['epaggelma'] :NULL;
  $email = (isset($_POST['mail'])) ? $_POST['mail'] : NULL;
  $username = (isset($_POST['username'])) ? $_POST['username'] : NULL;
  $password = (isset($_POST['password'])) ? $_POST['password'] : NULL;

//INSERT INTO Query Creation
$sqlQuery = "INSERT INTO registered_user ( age,email,fname,job,lname,password,username )
  VALUES ('$age','$email','$first_name','$job','$last_name','$password','$username')";

//MySQL connection
if( !( $database = mysql_connect( "localhost","root","" ) ) )//server name , a username , password
  die( "Αποτυχημένη σύνδεση στη βάση δεδομένων </body></html>" );//if false --> script gets terminated

//Opening database "htmlproject"
if( !mysql_select_db("htmlproject",$database) )//Database to be used , htmlproject
  die( "Αποτυχημένο άνοιγμα της htmlproject βάσης δεδομένων </body></html>" );

//Query
mysql_query( $sqlQuery, $database);
if( !( $result = mysql_query( $sqlQuery, $database) ) )
{
  print( "Αποτυχημένο προσπάθεια υποβολής ερωτήματος! <br />" );
  die( mysql_error() . "</body></html>" );
}else{
  print("Επιτυχής υποβολή ερωτήματος!");
}//end if

//Free resources
mysql_close( $database );

}//end ifisset
?><!--end php script.To be executed by server-->

<script type="text/javascript">//H εγγραφή ολοκληρώθηκε  επιστροφή στην αρχική σελίδα
var r=window.confirm("H εγγραφή ολοκληρώθηκε");
if( r == true){
  document.location.href = "SELIDA1.html";
}else{
    document.location.href = "SELIDA1.html";
}
</script>

</body>
</html>