$varaahash = md5($varaa);
$uidhash = md5($uid);
$varausid = $uidhash . $varaahash;
$query = "INSERT INTO varaukset (varausid, uid, varausaika) VALUES ('$varausid', '$uid', '$varaa')";

$starttime = time();
$today = strtotime(date('Y-m-d-9-00-00', $starttime));

for($i = 0; $i<= 4; $i++) {
        $slot = $today + ($i * 86400);
        $query = "select * from varaukset where uid='$uid' and varausaika='$slot'";
...