How to retrieve the firstname from database using session - php

Question

I want to display the firstname from database who login in my website - not the username of the user.
Here's a picture of my database so I already tried query but always complains about an undefined index
This is the navbar attendance only there's a another navbar too but I only example the attendance
navbar_attendance.php
<div class="navbar navbar-fixed-top navbar-inverse">
<div class="navbar-inner">
<div class="container">
<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</a>
<div class="nav-collapse collapse">
<ul class="nav">
<li><i class="icon-home icon-large"></i> Home</li>
<li><i class="icon-home icon-large"></i> Attendance Info</li>
<li><i class="icon-user icon-large"></i> Users</li>
<?php
include('dropdown.php');
?>
<li><i class="icon-book icon-large"></i> Books</li>
<li><i class="icon-group icon-large"></i> Member</li>
<li ><i class="icon-list-alt icon-large"></i> Archive</li>
<li><i class="icon-cog icon-large"></i> Utilities</li>
<li><i class="icon-signout icon-large"></i> Logout</li>
</ul>
<div class="pull-right">
<div class="admin">Welcome: <?php
if(isset($_SESSION['id'])){
// dont know what put in here
}
?></div>
</div>
</div>
</div>
</div>
</div>
<?php include('search_form.php'); ?>
session.php
<?php if(!isset($_SESSION)){
session_start();
} ?>
<?php
if (!isset($_SESSION['id']) || (trim($_SESSION['id']) == '')) {
?> <script>window.location='index.php';</script> <?php
exit();
}
$session_id=$_SESSION['id'];
?>

Answer 1

Hi you need to put this query at the place where you want to show the first name.
<?php if(!isset($_SESSION)){
session_start();
} ?>
<div class="navbar navbar-fixed-top navbar-inverse">
<div class="navbar-inner">
<div class="container">
<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</a>
<div class="nav-collapse collapse">
<ul class="nav">
<li><i class="icon-home icon-large"></i> Home</li>
<li><i class="icon-home icon-large"></i> Attendance Info</li>
<li><i class="icon-user icon-large"></i> Users</li>
<?php
include('dropdown.php');
?>
<li><i class="icon-book icon-large"></i> Books</li>
<li><i class="icon-group icon-large"></i> Member</li>
<li ><i class="icon-list-alt icon-large"></i> Archive</li>
<li><i class="icon-cog icon-large"></i> Utilities</li>
<li><i class="icon-signout icon-large"></i> Logout</li>
</ul>
<div class="pull-right">
<div class="admin">Welcome: <?php
if(isset($_SESSION['id'])){
$sql="SELECT firstname FROM TABLENAME WHERE user_id='$session_id'";
$result=mysqli_query($link,$sql);
if(mysqli_num_rows($result)>0)
{
while($row= mysqli_fetch_assoc($result)){
echo $row['firstname'];
}
}
}
?></div>
</div>
</div>
</div>
</div>
</div>
<?php include('search_form.php'); ?>`