perbaikan

<?php

if($_GET['id']==null){
    header('location:a.php');}
else
{
    $id=$_GET['id'];

    $koneksi=mysqli_connect("localhost","root","","belajar");
    $lihat=mysqli_query($koneksi,"select * from contoh where id='$id'");
    if($lihat){
        $row=mysqli_fetch_array($lihat);
        echo $row['nama'];
    }else{
        echo mysqli_error();
    }
}