test1/public/drupal-8.3.1/modules/user_import/user_import....

<?php
/**
 * Install file for User Import module
 * Date of creation: 17.05.2017
 * Creator: Yuliia Polna
 * TODO:
 *  - make normal test db
 *  - manage updating of module
 *  - add logs
 */

use Drupal\user_import\Service\MysqlConnectService;
use Drupal\user_import\Service\AddUserService;

function user_import_install(){
    $servername = "localhost";
    $username = "root";
    $password = "Abccpm80";
    $dbname = "test";

    $dbConnect = new MysqlConnectService();
    $addUser = new AddUserService();
    $connection = $dbConnect->connect($servername,$username,$password,$dbname);
    $query = "SELECT * FROM adsuser WHERE access='MITARBEITER' ";
    $result = mysqli_query($connection,$query) or die("Query failed");
    $i = 0; //
    while ($row = mysqli_fetch_array($result)) {
        if ($i < 3) { //
            if(!($addUser->checkIfExists(utf8_encode($row['username'])))) {
                $addUser->createUser($row);
            }
            $i++; //
        } else { //
            break; //
        } //
    }
}