Help with update record process

[hubbardude]

I'm trying to enable a simple updating capability to a website. On one of the pages I have a list of current shows for a band. If one of the band members is logged in they can update show information. Here is the code for that page:

<?php
$query = "SELECT * " .
"FROM shows" ;
$result = mysql_query($query, $link)
or die(mysql_error());
$num_shows = mysql_num_rows($result);

$show_details = '';
while ($row = mysql_fetch_array($result)) {
$show_id = $row['show_id'];
$show_date = $row['show_date'];
$show_venue = $row['show_venue'];
$venue_url = $row['venue_url'];
$venue_address = $row['venue_address'];
$venue_phone = $row['venue_phone'];
$venue_maplink = $row['venue_maplink'];

$show_details .=<<<EOD
<h3>$show_date</h3>
<p><a href="$venue_url">$show_venue</a><br />
$venue_address&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a href="$venue_maplink">Map it</a><br />
$venue_phone</p>
<a href="editshow.php?cmd=edit&show_id=$show_id">Edit show</a><hr />
EOD;
}

echo $show_details;
?>

Then, the link takes them to a page with the populated form fields where they can make the changes and submit. The code for that page:

<?php

if($GET["cmd"]=="edit" || $POST["cmd"]=="edit")
{
if (!isset($POST["submit"]))
{
$show_id = $GET["show_id"];
$sql = "SELECT * FROM shows WHERE show_id=$show_id";
$result = mysql_query($sql);

$myrow = mysql_fetch_array($result);
?>

  <form action="<?=$_SERVER["PHP_SELF"]?>" method="post">
  <input type=hidden name="show_id" value="<?php echo $myrow["show_id"] ?>">

  Show Date:<INPUT TYPE="text" NAME="show_date" VALUE="<?php echo $myrow["show_date"] ?>"><br />
  Show Venue<INPUT TYPE="text" NAME="show_venue" VALUE="<?php echo $myrow["show_venue"] ?>"><br />
  Venue Url:<INPUT TYPE="text" NAME="venue_url" VALUE="<?php echo $myrow["venue_url"] ?>"><br />
  Venue Address:<INPUT TYPE="text" NAME="venue_address" VALUE="<?php echo $myrow["venue_address"] ?>"><br />
  Venue Phone:<INPUT TYPE="text" NAME="venue_phone" VALUE="<?php echo $myrow["venue_phone"] ?>"><br />
  Venue Maplink:<INPUT TYPE="text" NAME="venue_maplink" VALUE="<?php echo $myrow["venue_maplink"] ?>"><br />

  <input type="hidden" name="cmd" value="edit">

  <input type="submit" name="submit" value="submit">

  </form>

<? } ?>

<?
if (isset($POST["submit"]))
{
$show_id = "show_id";

$show_date = $POST["show_date"];
$show_venue = $POST["show_venue"];
$venue_url = $POST["venue_url"];
$venue_address = $POST["venue_address"];
$venue_phone = $POST["venue_phone"];
$venue_maplink = $_POST["venue_maplink"];

  $sql = "UPDATE shows SET show_date='$show_date',show_venue='$show_venue',venue_url='$venue_url', venue_address='$venue_address',venue_phone='$venue_phone',venue_maplink='$venue_maplink' WHERE show_id=$show_id";

  $result = mysql_query($sql);
  echo "Thank you! Information updated.";

}
}
?>[/COLOR]

But on submittion of the data, I get an error:

Notice: Undefined index: cmd in C:\Apache2.2\htdocs\Devils\editshow.php on line 30
and the information isn't updated.

I'm kind of new so it may be something obvious. Also, if there's a better way to do this I'm open to ideas. Thanks.

[future448]

Your Undefined index is because of this line:

if($_GET["cmd"]=="edit" || $_POST["cmd"]=="edit")

Because cmd will either be sent by POST or GET so one will always be undefined.

Instead use:

if(isset($_REQUEST['cmd']) && ($_REQUEST['cmd'] == 'edit'))

Your form is not updating because this line:

$show_id = "show_id";

Should be:

$show_id = $_POST['show_id'];