phpでMySQLに接続する書き方

phpでMySQLに接続, sql文にてデータを挿入する書き方例
$stmt->executeにて実行しています。変数の$dbhはdbhandlerの略です。

  try {
    $dbh = new PDO('mysql:host='/DB_HOST.';dbname='.DB_NAME,DB_USER,DB_PASSWORD);
  } else (PDOException $e){
    echo $e->getMessage();
    exit;
  }

  $stmt = $dbh->prepare("select * from users where instagram_user_id=:user_id limit 1");
  $stmt->execute(array(":user_id"=>$json->user->id));
  $user = $stmt->fetch();

if (empty($user)){
    $stmt = $dbh->prepare("insert into users(instagram_user_id, instagram_user_name, instagram_profile_picture, instagram_access_token, created, modified) values (:user_id, :user_name, :profile_picture,  :access_token, now(), now());");
    $pramas = array(
      ":user_id" =>$json->user->id,
      ":user_name" =>$json->user->username,
      ":profile_picture" =>$json->user->profile_picture,
      ":access_token"=>$json->access_token
    );
    $stmt->execute($params);

データの取得

$stmt = $dbh->prepare("select * from users where id=:last_insert_id limit 1");
    $stmt->execute(array(":last_insert_id"=>$dbh->lastInsertId()));
    $user = $stmt->fetch();