Все я сделал, только без нажатия кнопки, обновление на странице происходит по клику:
if (!empty($_POST['nazv_ciklovKomis']) && !empty($_POST['nazv_specialnosti']) && !empty($_POST['nazv_groups'])&& !empty($_POST['lastname'])); {
}
echo '<input name="disc" type="submit" value="Вывести" onchange=\"this.form.submit();\"/>';
echo '<p><table border = "1">
<tr>
<th>Название дисциплины</th>
<th>Вид контроля</th>
<th>Оценка</th>
<th>Дата сдачи</th>
</tr>';
$result = mysql_query ("SELECT nazv_discipline, vid_kontrolya, otsenka, date_sdachi
FROM Students, Discipline, Uspevaemost
WHERE Students.id_student= '" . addslashes($_POST['lastname']) . "'
AND Students.id_student=Uspevaemost.id_student AND Discipline.id_Discipline=Uspevaemost.id_Discipline",$db);
while ($myrow = mysql_fetch_array ($result)){
$nazv_discipline = $myrow["nazv_discipline"];
$vid_kontrolya = $myrow["vid_kontrolya"];
$otsenka = $myrow["otsenka"];
$date_sdachi = $myrow["date_sdachi"];
echo "<tr>";
echo "<td>$nazv_discipline</td>";
echo "<td>$vid_kontrolya</td>";
echo "<td>$otsenka</td>";
echo "<td>$date_sdachi</td>";
echo "</tr>";
}
if (!empty($_POST['nazv_ciklovKomis']) && !empty($_POST['nazv_specialnosti']) && !empty($_POST['nazv_groups'])&& !empty($_POST['lastname']) && !empty($_POST['nazv_discipline'])); {
}
mysql_close($db);
echo '</table>';
echo "</form>";
?>