_db_data.php

<?php
$db_host = 'localhost';
$db_name = 'class_db';
$db_user = 'wii';
$db_pass = 'qwer1234';
$db_charset = 'utf8';
$db_collate = 'utf8_unicode_ci';

$dsn = "mysql:host={$db_host};dbname={$db_name};charset={$db_charset}";

$pdo_options = [
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_PERSISTENT => false,
    PDO::ATTR_EMULATE_PREPARES => false,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
    PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES {$db_charset} COLLATE
    {$db_collate}"
    ];
    try {
    $pdo = new PDO($dsn, $db_user, $db_pass, $pdo_options);
    } catch(PDOException $ex) {
    echo 'Connection failed:'. $ex->getMessage();
    }
    if(! isset($_SESSION)){
    session_start();
    }