<?php
class Test
{
  // database object
  private $pdo;

  public function __construct($servername, $username, $password, $dbname) {
    // open database connection.
    $dsn = "mysql:dbname=" . $dbname . ";host=" . $servername;
    $this->pdo = null;

    // create/check connection
    try {
      $this->pdo = new PDO($dsn, $username, $password);
    } catch (PDOException $e) {
      print('Connection failed: ' . $e->getMessage());
      die();
    }
  }

  public function __destruct() {
    // close database connection.
    $this->pdo = null;
  }

  public function search_address($input,$sql) {
    $stmt = $this->pdo->prepare($sql);
    $stmt->bindParam(':arg', $input);
    $stmt->execute();
    return $stmt->fetchAll();
  }
}

$servername = "127.0.0.1"; // データベース稼働ホストのホスト名
$username = "shizutaro";   // データベースのアクセス権を持つユーザ名
$password = "at_ad437";   // 上記ユーザのパスワード
$dbname = "CSexp1DB";//データベース名
$input_arg = 2;
$sql ="select * from table name where id = :arg";
$postal = new Test($servername, $username, $password, $dbname);
$result = $postal->search_address($input_arg, $sql);
?>