berikut kode actionnya gan

?php



include "config.php";

 $nama=$_POST['nama'];

 $foto=$_FILES['foto'];

 $nama_gambar=$_FILES['foto']['name'];

 $size=$_FILES['foto']['size'];

 $tipe_gambar=$_FILES['foto']['type'];

 $lokasi_file= $_FILES['foto']['tmp_name'];

 $folder="img/$foto";



if(!empty($lokasi_file)){

 move_uploaded_file($lokasi_file,$folder);



 $query="UPDATE vendor SET foto='$foto' WHERE username='$nama'";

 $hasil=mysqli_query($koneksi,$query);

 if($hasil){

 header('Location:gantiprofil.php');

 }else{

 echo "gagal <h1></h1>";

 }

}

Berikut Form input filenya 

<form action="ganti_foto_act.php" method="post" enctype="multipart/form-data">

 <div class="form-group">

 </div>

 <div class="row">

 <div class="file-field input-field col xl4">

 <input type="hidden" name="nama" value="<?php echo $data['username'];?>">

 <div class="btn">

 <span>Foto</span>

 <input name="foto" type="file">

 <input name="x" type="hidden" id="x" >

 </div>

 <div class="file-path-wrapper">

 <input class="file-path validate" type="text">

 </div>

 </div>

 </div>

 <div class="form-group">

 <label></label>

 <input type="submit" class="btn btn-info" name="update" value="Ganti">

 <input type="reset" class="btn btn-danger" value="reset">

 </div> 

 </form>