how to get single row data in table php - php

Question

This is the main table which shows all the data from database, when I click the print it should only print the that row but it does not show up I get "Undefined variable: row" and im starting to think this has to do with this here the code for the table:
<div class="container" >
<div class="well" ">
<span class="pull-right"><a data-toggle="modal" data-target="#myModal" href="#myModal" class="btn btn-primary"><span class="glyphicon glyphicon-plus"></span> Enroll Pupil</a></span>
<div>
</div>
<table class="table table-striped table-bordered table-hover" >
<thead>
<th >Moble Number</th>
<th >First Name</th>
<th>Last Name</th>
<th>Section</th>
<th>Grade</th>
<th>Action</th>
</thead>
<tbody>
<?php
include('conn.php');
$query=mysqli_query($conn,"select * from `tbl_students`");
while($row=mysqli_fetch_array($query)){
?>
<tr s>
<td><?php echo $row['LRN']; ?></td>
<td><?php echo $row['FirstName']; ?></td>
<td><?php echo $row['LastName']; ?></td>
<td><?php echo $row['Section']; ?></td>
<td><?php echo $row['GradeLevel']; ?></td>
<td >
<span class="glyphicon glyphicon-edit"></span> Edit | |
<span class="glyphicon glyphicon-trash"></span> Delete | |
<span class="glyphicon glyphicon-edit"></span> Add Subject | |
<a class="btn btn-success" onclick="window.open('IndivPrintTableStudent.php').print();">Print</a>
<?php include('buttonstudent.php'); ?>
</td>
</tr>
<?php
}
?>
</tbody>
here is my database
<?php include"includes/config.php" ?>
<link rel="stylesheet" type="text/css" href="Print.css" media="print"></link>
<div class="container" >
<table>
<thead>
<th style="border: 3px solid #2F323A; text-align: center; padding-bottom: 8px;">Moble Number</th>
<th style="border: 3px solid #2F323A; text-align: center; width: 14%;">First Name</th>
<th style="border: 3px solid #2F323A; text-align: center; width: 14%;">Last Name</th>
<th style="border: 3px solid #2F323A; text-align: center; padding-bottom: 9px;">Section</th>
<th style="border: 3px solid #2F323A; text-align: center; width: 10%;">Grade</th>
</thead>
<tbody>
<?php
$query=mysqli_query($con,"SELECT * FROM tbl_students WHERE LRN='".$row['LRN']."'");
while($row=mysqli_fetch_array($query)){
?>
<tr style="background-color: #f0f8ff; border: 3px solid #2F323A;">
<td style="border: 3px solid #2F323A; padding-top: 15px; color: #2F323A;"><?php echo $row['LRN']; ?></td>
<td style="border: 3px solid #2F323A; padding-top: 15px; color: #2F323A;"><?php echo $row['FirstName']; ?></td>
<td style="border: 3px solid #2F323A; padding-top: 15px; color: #2F323A;"><?php echo $row['LastName']; ?></td>
<td style="border: 3px solid #2F323A; padding-top: 15px; color: #2F323A;"><?php echo $row['Section']; ?></td>
<td style="border: 3px solid #2F323A; padding-top: 15px; color: #2F323A;"><?php echo $row['GradeLevel']; ?></td>
</tr>
<?php
}
?>
</tbody>
</table>
</div>
how do I get single data in individual manner? the error that I get s "Undefined variable: row" which you can see on the query. i dont know why it says that I only made this is table form just to see if i can get the actual data from a single student. I hope my question can be understandable.

Answer 1

Your button is linking to IndivPrintTableStudent.php but you aren't passing the ID of the clicked row in the URL, so that script doesn't know which row you wanted to display. $row['LRN'] in the second script isn't going to exist because it's part of a different script, variables are not carried across automatically from one script to another. You have to pass them in the URL.
You'd have something like
onclick="window.open('IndivPrintTableStudent.php?LRN=<?php echo $row["LRN"]; ?>').print();
in the print button on the first table.
And then the second script would use $_GET["LRN"] to retrieve that value from the URL and use it in the sql query.
(Beware of SQL injection though, learn how to use parameters and prepared statements to protect your database - see https://phpdelusions.net/mysqli for examples.)