come inserire un record con checkbox

[prinzart]

percaso devo fare cosi?

<?php
if ($riga==5){
$sql = "INSERT INTO a_corsi (nome_corso)
VALUES ('$nome_corso')";

mysql_query($sql, $conn) or die ($sql);
$msg = "corso inserito nel database";
} 
elseif ($riga==3){
    $sql = "SELECT nome_corso FROM a_corsi WHERE id_corsi=$corso";
    $result = mysql_query($sql,$conn);
    $row = mysql_fetch_array($result);
} 
?>

<form enctype="multipart/form-data" name="form" action="<?=$PHP_SELF?>" method="post">
<?
if ($riga!=3){?>
nome corso <input name="nome_corso" type="text" size="18" maxlength="30">
<input name="submit" type="submit" class="pulsante" value="inserisci"><input type="hidden" name="riga" value="5">
<?
    if ($msg){?>
      <span class="testo_viola_bold">
      <?=$msg?>
      </span>
      <?
        }?>

<table width="650" border="0" cellspacing="0" cellpadding="0"> 
<tr> 
    <td height="1" colspan="4" bgcolor="BF9BB5"></td> 
    </tr> 
                              <? 
                          $i=1; 
                        $sql = mysql_query("SELECT * FROM a_materie ORDER BY nome_materia") or die(mysql_error()); 
                        while($row=mysql_fetch_array($sql)){ 
                            if ($i==1){ echo "<tr>";} ?> 
              <td height="41" width="216"> 
<span class="testo_grigio_bold">[img]../images/menu_triangolo.gif[/img]<?=$row['nome_materia']?> <input type="checkbox" name="nome_materia" value="1"></span> 
</td> 
                  <? 
                            if ($i==3){ 
                                echo "<td width=\"2\"></td></tr><tr> 
    <td height=\"1\" colspan=\"4\" bgcolor=\"BF9BB5\"></td> 
    </tr>"; 
                                $i=0; 
                            } 
                             $i++; 
                        }?> 
                          </table> 

     
<? 
    } elseif ($riga==3){?>

</form>