//แก้ไขข้อมูล
    $sname="";
    $id="";
    $lname="";
    $gender="";
    $data="";
    $age="";
    $address="";
    $phone="";
    $sqledit="select * from employee where id=" . $_GET['id'];
    $resultedit=mysqli_query($con,$sqledit);
    while($row=mysqli_fetch_assoc($resultedit)){
        $sname = $row['sname'];
        $id = $row['id'];
        $lname=$row['lname'];
        $gender=$row['gender'];
        $data=$row['data'];
        $age = $row['age'];
        $address=$row['address'];
        $phone = $row['phone'];
}
............................................................................................................................
<?php
    $sql="select * from employee";
    $result=mysqli_query($con,$sql);
    while($row=mysqli_fetch_assoc($result)){
        //แสดงผล
        echo '<tr>
                <td>'.$row['id'].'</td>
                <td>'.$row['sname'].'</td>
                <td>'.$row['lname'].'</td>
                <td>'.$row['gender'].'</td>
                <td>'.$row['data'].'</td>
                <td>'.$row['age'].'</td>
                <td>'.$row['address'].'</td>
                <td>'.$row['phone'].'</td>
                
                <td>
                <a href="edit_employee.php?id='.$row['id'].'" class="btn btn-success"><i class="glyphicon glyphicon-pencil"></i></a>
                <a href="#" onclick="dialog('.$row['id'].');" class="btn btn-danger"><i class="glyphicon glyphicon-trash"></i></a>
                </td>
             </tr>';  
        
        
    }
    
?>