Update the table data in mysql - php

Question

I have a table which fetch the data from database except the issued column. The number of row in that table is not fixed. There is an update button and which update the record. After entering the value in issued column i update that record.My data is not updating in the table . I have doubt how to give name to to the td element of the table.Code for table is
<form role="form" method="post" class="form-inline">
<table >
<thead>
<tr >
<th width="50px" >Sl.No.</th>
<th style="display:none;" >Txn ID.</th>
<th width="175px">Stationery Type</th>
<th width="73px">REQUESTED</th>
<th width="73px">ISSUED</th>
</tr>
</thead>
<tbody>
<tr class="table-row-2" >
<td> <?php echo htmlentities($cnt);?></td>
<td style="display:none;"><?php echo htmlentities($result->txnid);?></td>
<td><?php echo htmlentities($result->stationerytype);?></td>
<td><?php echo htmlentities($result->REQUESTED);?></td>
<td><input type="number" name="stationeryqtyissued" > </td>
</TABLE>
<input type="submit" name="submit" value="Submit" class="btn pull-right" style="margin-left:375px; margin-bottom:30px;">
</form>
Mysql code to update database is
if(isset($_POST['submit']))
{
$samplecount=$_GET["total"];
for($i=0;$i<$samplecount;$i++){
$status="issued";
$txnid=$_POST['txnid'];
$stationeryqtyissued=$_POST['stationeryqtyissued'];
$sql="update tblstationerystock set status=:status,stationeryqtyissued=:stationeryqtyissued where txnid=:txnid";
$query = $dbh->prepare($sql);
$query->bindParam(':status',$status,PDO::PARAM_STR);
$query->bindParam(':stationeryqtyissued',$stationeryqtyissued[$i],PDO::PARAM_STR);
$query->bindParam(':txnid',$txnid[$i],PDO::PARAM_STR);
$query->execute();
$_SESSION['msg']="Stationery Added successfully";

Answer 1

Add the following line to you form
<input type="hidden" id="txnid" name="txnid" value="<?php echo htmlentities($result->txnid);?>">
If you want to send an array
<input type="hidden" name="txnid[]" value="<?php echo htmlentities($result->txnid);?>">
then you would have more than one row for that to work
and you can then
get it by
$txnid=$_POST['txnid'];
But that is no array, so that should be valid
$query->bindParam(':stationeryqtyissued',$stationeryqtyissued,PDO::PARAM_STR);
$query->bindParam(':txnid',$txnid,PDO::PARAM_STR);
So i am unclear why you are running a loop for the update over $total that i also don't see in your form.
<td style="display:none;"><?php echo htmlentities($result->txnid);?></td>
Would not send data to your php with POST or GET