sc gan

<?php
$connection = mysql_connect("localhost", "root", "");
$db = mysql_select_db("tes_db", $connection);
$nama = $_POST['nama'];
$username = $_POST['username'];
$password = $_POST['password'];
if (empty($nama)){
echo "<script>alert('Nama belum diisi')"</script>;
echo "<meta http-equiv='refresh' content='1' url='daftar.php'>";
}
else
if(empty($username)){
echo "<script>alert('Username belum diisi')</script>";
echo "<meta http-equiv='refresh' content='1' url='daftar.php'>";
}
else
if (empty($password)){
echo "<script>alert('Password belum diisi')</script>";
echo "<meta http-equiv='refresh' content='1' url='daftar.php'>";
}
else
{
$daftar = mysql_query("INSERT INTO db_tes (id_siswa,nama_siswa,user_siswa,pass_siswa) values
'$nama','$username','$password')");
if($daftar){
echo "<script>alert('Berhasil Mendaftar')</script>";
echo "<meta http-equiv='refresh' content='1' url='daftar.php'>";
}
}
else
{
echo "<script>alert('Gagal Mendaftar')</script>";
echo "<meta http-equiv='refresh' content='1' url='daftar.php'>";
}
?>