php update sql database from form
<?php
include "config.php"; // Using database connection file here
$id = $_GET['id']; // get id through query string
$qry = mysqli_query($db,"select * from emp where id='$id'"); // select query
$data = mysqli_fetch_array($qry); // fetch data
if(isset($_POST['update'])) // when click on Update button
{
    $fname = $_POST['fname'];
    $lname = $_POST['lname'];
	
    $edit = mysqli_query($db,"update emp set fname='$fname', lname='$lname' where id='$id'");
	
    if($edit)
    {
        mysqli_close($db); // Close connection
        header("location:all_records.php"); // redirects to all records page
        exit;
    }
    else
    {
        echo mysqli_error();
    }    	
}
?>
<h3>Update Data</h3>
<form method="POST">
  <input type="text" name="fname" value="<?php echo $data['fname'] ?>" placeholder="Enter Full Name" Required>
  <input type="text" name="lname" value="<?php echo $data['lname'] ?>" placeholder="Enter Last Name" Required>
  <input type="submit" name="update" value="Update">
</form>