$host="localhost";
    $username="root";
    $password="sunbuggy";
    $database="mpg";
    $table="m";

mysql_connect($host,$username,$password) or die( "unable to connect to mysql server");
    mysql_select_db($database) or die( "Unable to select database");

        $driver=$_POST['driver'];
        $shuttle=$_POST['shuttle'];
        $gas=$_POST['gas'];
        $miles=$_POST['miles'];
        $cost=$_POST['cost'];

$getlastpri= "(SELECT * FROM '$table' ORDER BY `prikey` DESC)";


$sql=mysql_query($getlastpri);
$i=0;
$num=mysql_result($prime,$i,$prikey);
$shut=NULL;
while ($shut != $shuttle){
$shut=mysql_result($sql,$i,shuttle);
    $i++;}
if($shut == $shuttle)
    {$pastmiles=mysql_result($sql,$i,miles);}
else
    $pastmiles=Null;


if($pastmiles=Null):
    {$milestravled=Null;}
else:
$milestravled=$miles-$pastmiles;

$milespergallon=($milestravled/$gas);



$abc= "INSERT INTO $table VALUES ('','$driver','$shuttle','$gas','$miles','$cost', '$milestravled','$milespergallon')";
mysql_query($abc);

mysql_close();
echo "Your latest information has been input into the server";
?>`

$getlastpri= "(SELECT * FROM '$table' ORDER BY `prikey` DESC)";

$getlastpri= "SELECT * FROM `$table` ORDER BY `prikey` DESC";

if($pastmiles=Null):
{$milestravled=Null;}
else:

if($pastmiles == Null){
    $milestravled=Null
}

<?
if($a):
    echo $a;
    if($b) {
      echo $b;
    }
else:
    echo $c;
endif;
?>

if($pastmiles=Null):
    {$milestravled=Null;}
else:
    $milestravled=$miles-$pastmiles;

if (NULL == $pastmiles)
    ...