config.php

$con = new mysqli (
## Enter your MySQL connection information below! ##
   'localhost', /*host*/
   'root', /*Username*/
   '', /*password*/
   'testdb' /*dbname*/
);

   if (mysqli_connect_errno()) {
      printf("Connection failed: ", mysqli_connect_error());
   }
   mysqli_select_db($con,"testdb");

mysqli_close($con)