Why Session Variable Sending only last row data to another page - php

Question

here the problem is i need to view the whole row data in view details page when the button is clicked but when i click the last row data is sent through session variable and last row is displayed but i need particular row to display fully when the name is selected of the employee. please help me out in this .
thank you
index.php
<?php
include('connection.php');
$sql = "SELECT empname,salary,contact_no,department,empdesg FROM add_emp ORDER BY empname ASC ";
$result = $con->query($sql);
if ($result->num_rows > 0)
{
// output data of each row
?>
<center>
<table cellpadding="20px" cellspacing="40px;" border="2px" align="center" width="device">
<tr>
<th>Name</th>
<th>Department</th>
<th>Designation</th>
<th> </th>
<?php
while($row = $result->fetch_assoc())
{
$name='';
$name=$row["empname"];
$department=$row["department"];
$designation=$row["empdesg"];
?>
</tr>
<td>
<?php echo $name?>
</td>
<td>
<?php echo $department?>
</td>
<td>
<?php echo $designation?>
</td>
<td><a href="viewdetails.php">
<button>Details</button>
</a>
<?php
$_SESSION['name']= $name;
?>
</td>
<?php
}
}
else {
echo "0 results";
}
?>
viewdetails.php
<?php
session_start();
include('connection.php');
$sql="select * from add_emp where empname='$_SESSION[name]'";
$result = mysqli_query($con, $sql); // First parameter is just return of "mysqli_connect()" function
echo "<br>";
echo " <table cellpadding='5px' cellspacing='10px' border='1px' align='center'>";
while ($row = mysqli_fetch_assoc($result))
{ // Important line !!! Check summary get row on array ..
echo "<tr>";
echo "<th>" ."Name". "</th>";
echo "<td>" .$row['empname']. "</td>";
echo "</tr>";
echo "<tr>";
echo "<th>" ."DOB". "</th>";
echo "<td>" .$row['eage']. "</td>";
echo "</tr>";
echo "<tr>";
echo "<th>" ."Adhaar Number". "</th>";
echo "<td>" .$row['adhaar']. "</td>";
echo "</tr>";
echo "<tr>";
echo "<th>" ."Address". "</th>";
echo "<td>" .$row['address']. "</td>";
echo "</tr>";
echo "<tr>";
echo "<th>" ."Salary". "</th>";
echo "<td>" .$row['salary']. "</td>";
echo "</tr>";
echo "<tr>";
echo "<th>" ."Phone Number". "</th>";
echo "<td>" .$row['contact_no']. "</td>";
echo "</tr>";
echo "<tr>";
echo "<th>" ."Department". "</th>";
echo "<td>" .$row['department']. "</td>";
echo "</tr>";
echo "<tr>";
echo "<th>" ."Designation". "</th>";
echo "<td>" .$row['empdesg']. "</td>";
echo "</tr>";
echo "<tr>";
}
echo "</table>";
?>