<div class="custom_search col-md-5">
       <span>
         <select class="form-control" name="column_names" id="column_names">
             <option value="keten1">" . $row['keten'] . "</option>"
         </select>
       </span>
    </div>

//database login informatie
$host = '';
$port = '';
$dbname = '';
$user = '';
$password = '';

$conn = pg_connect("host=$host port=$port dbname=$dbname user=$user password=$password");
if (!$conn) {
    echo "Not connected : " . pg_error();
    exit;
}

$sql_column_select = "SELECT column_name FROM information_schema.columns WHERE table_name='fastfood_g'";