MySQLandPHPBasicsExercise_7.CallCenterApplication

// file CallCenter.php
<?php
class CallCenter{
    private $dbi = false;

    public function connectDB()
    {
        $db = new Database();
        $this->dbi = $db->connect();
    }

    public function __construct()
    {
        $this->connectDB();
    }

    public function main()
    {
        do{
            $input_str = trim(fgets(STDIN));
            $res = $this->getCountryInfo($input_str);
            if($res != false){
                $flag = false;
                foreach ($res as $i=>$iv){
                    echo "Country: " . $iv['country_name'] . "\r\n";
                    echo "Capital: " . $iv['capital'] . "\r\n";
                    $flag = true;
                    break;
                }
                if($flag == false){
                    echo "Country not found.";
                }
            }else{
                echo "Could not read from DB.";
            }
        }
        while($input_str != 'Bye');
    }

    private function getCountryInfo($str)
    {
        $result = $this->dbi->query("
            SELECT `country_name`, `capital`
            FROM `countries`
            WHERE `country_name` = \"$str\"
            OR `country_code` = \"$str\"
                    OR `iso_code` = \"$str\"
                    LIMIT 0,1 ");

        if (is_object($result)){
            return($result);
        }
        else{
            return false;
        }

    }
}

// file Database.php
<?php
class Database extends PDO
{
    private $db_host = "localhost";
    private $db_name = "geography";
    private $db_user = "root";
    private $db_password = "";
    private $db = false;

    public function __construct()
    {
        parent::__construct("mysql:dbname=" . $this->db_name . ";host=" . $this->db_host, $this->db_user, $this->db_password);
    }

    public function setErrorExeption()
    {
        $this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    }

    public function connect()
    {
        $this->setErrorExeption();
        return $this;
    }
}

// file callcenter_app.php
<?php
include 'Database.php';
include 'CallCenter.php';

$app = new CallCenter();
$app->main();