Trying to update dates in database with dynamically created forms - php

Question

So i've created an administration page that creates X-number of forms based on how many users we have in our database, each of which have a submit button next to them to submit changes to the dates we have in our DBs. My problem is that when I want to get the value of what gets posted I can't extract exactly what I need from what gets posted. It gets saved into an array called and when I print_r the array I get exactly what I want, which is:
[1] => "whatever date they typed in"
(obviously the 1 changes depending on which item they changed the date of)
I need be able to query my datebase by:
UPDATE users SET subdate="whatever they typed in" WHERE id="the array reference number"
I know exactly what I need to do, I'm just not as familiar with SQL as i'd like to be, so any help would be greatly appreciated. Thanks in advance.
Code for reference:
<div class="form-section grid12" id="changedates">
<h1>Change Dates</h1>
<?php
$query = mysql_query("SELECT * FROM users WHERE admin='y'");
?>
<table>
<?php
while($row = mysql_fetch_assoc($query)) {
?>
<tr>
<td>
<h5><?php echo $row['displayname'];?></h5>
</td>
<td>
<form action="" method="POST">
<input type="text" name="subdate[<? echo $row['id'] ?>]" value="<?php echo $row['submissiondate'];?>">
<input type="text" name="nextupdate[<? echo $row['id'] ?>]" value="<?php echo $row['nextupdate'];?>">
</td>
<td>
<input type="submit" value="Set Date" name="setdate">
</form>
</td>
<?php
}
?>
</table>
</div>

Answer 1

You could use foreach...
foreach ($_POST[nextupdate] as $rowId => $time)
{
// do db update
}
Edit: Just realised you have more than one input per form.
Why not name each input with an array name:
<input type="text" name="form_data[<?= $row_id ?>][subdate]">
<input type="text" name="form_data[<?= $row_id ?>][nextupdate]">
In PHP:
foreach ($_POST[form_data] as $rowId => $values)
{
$subdate = $values[subdate];
$nextupdate = $values[nextupdate];
// do SQL stuff
}