SQL contar numero de lineas que devuelve la consulta

$result = mysql_query("select * from valtar where vtatar='1'");
if (!$result)
{
die('Invalid query: ' . mysql_error());
}

$num = mysql_num_rows($result);

echo $num;

//********************************************************************
// si es un update o un delete o un insert

mysql_query('DELETE FROM mytable WHERE id < 10');
printf("Records deleted: %d\n", mysql_affected_rows());