PHP : GANTI TABEL

$koneksi=mysql_connect("localhost","","") or die ("Koneksi gagal");

$tabel_lama="mahasiswa_baru";
$tabel_baru="mahasiswa";

$sql="ALTER TABLE $tabel_lama RENAME $tabel_baru";
$qry=mysql_db_query("contoh",$sql,$koneksi);

if ($qry) {
print "Nama tabel telah berubah";
} else {
print "Nama tabel gagal berubah";
}
mysql_close();
?>