Not quite sure what you're up to here. So I'll assume that you're updating the record associated with the 'namn'?
In that case, assuming each record is autoindexed, use the id number instead:
do{
printf("<tr><td>%s</td><td><input type=checkbox name=\"deltagare".$myrow['id']."\" value=\"0\" checked></td></tr>", $myrow['namn']);
$a++;
}while ($myrow = mysql_fetch_array($result));
if ($submit == "Update"){
while (list($key, $value) = each($HTTP_POST_VARS)) {
//if other form elements...I guess a regex expression works too.
$searched = "deltagare";
$len = strlen($searched);
if (substr($key, 0, $len) == $searched){
$num = str_replace($searched,"",$key);
$sql = "UPDATE members SET status = 1 WHERE id = $num";
$result = mysql_db_query ($dbname,$sql);
}
}
If a checkbox is not checked, it will not get passed to $HTTP_POST_VARS.
Hope this helps.