Is this this mysql/php correct to delete a row?
<?php
$id = $_POST['dr'];
$dbhost = 'star***.***.edu';
$dbuser = '***4123';
$dbpass = '*****';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
  die('Could not connect: ' . mysql_error());
}
$sql = "DELETE FROM address
        WHERE idnum="".$id"";

mysql_select_db('***4123');
$retval = mysql_query( $sql, $conn );
if(! $retval )
{
  die('Could not delete data: ' . mysql_error());
}
echo "Deleted data successfullyn";
mysql_close($conn);
?>

$sql = "DELETE FROM address WHERE idnum = " . $id;

$id = (int) $_POST [ 'dr' ];

<?php
  try {
    $db = new PDO ('mysql:host=star***.***.edu;dbname=***4123', '***4123', '*****');
  }

  catch (Exception $e)
  {
    die('Could not connect: ' . $e->getMessage());
  }

  $statement = $db->prepare('DELETE FROM address WHERE idnum=?');

  $statement->bindParam(1, $_POST['dr']);

  if (false === $statement->execute())
  {
    die('Could not delete data: ' . print_r($pdo->errorInfo(),true));
  }

<?php
$id = mysql_real_escape_string($_POST['dr']);
$dbhost = 'star***.***.edu';
$dbuser = '***4123';
$dbpass = '*****';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
  die('Could not connect: ' . mysql_error());
}
$sql = "DELETE FROM address
        WHERE idnum= '$id' ";

mysql_select_db('***4123');
$retval = mysql_query( $sql, $conn );
if(! $retval )
{
  die('Could not delete data: ' . mysql_error());
}
echo "Deleted data successfullyn";
mysql_close($conn);
?>