PDOで条件付き検索

<?php

define('DB_DATABASE', 'name_db');
define('DB_USERNAME', 'dbuser');
define('DB_PASSWORD', 'xxxx');
define('PDO_DSN', 'mysql:dbhost=localhost;dbname=' . DB_DATABASE);

try {
  $db = new PDO(PDO_DSN, DB_USERNAME, DB_PASSWORD);
  $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

  // $stmt = $db->prepare("select score from users where score > ?");
  // $stmt->execute([60]);

  //$stmt = $db->prepare("select name from users where name like ?");
  //$stmt->execute(['%t%']);

  $stmt = $db->prepare("select score from users order by score desc limit ?");
  $stmt->bindValue(1, 1, PDO::PARAM_INT);
  $stmt->execute();

  $users = $stmt->fetchAll(PDO::FETCH_ASSOC);
  foreach($users as $user){
    var_dump($user);
  }
  echo $stmt->rowCount() . "records found.";

  /*
  (1) exec(): 結果を返さない、安全なsql
  (2) query(): 結果を返す、安全、何回も実行されない
  (3) prepare(): 結果を返す、安全対策が必要、複数回実行
  */

  // $stmt = $db->prepare("insert into users(name, score) values(?, ?)");
  // $stmt->execute(['tagu', 44]);
  // $stmt = $db->prepare("insert into users(name, score) values(:name, :score)");
  // $stmt->execute(['name'=>'nishikawa', ':score'=>76]);
  // echo "inserted: " . $db->lastInsertId();

  // bindValue 値をbind
  // bindParam 変数への参照をbindValue

  // $stmt = $db->prepare("insert into users(name, score) values(?, ?)");

  // $name = 'tagu';
  // $stmt->bindValue(1, $name, PDO::PARAM_STR);
  // $score= 23;
  // $stmt->bindValue(2, $score, PDO::PARAM_INT);
  // $stmt->execute();
  // $score= 44;
  // $stmt->bindValue(2, $score, PDO::PARAM_INT);
  // $stmt->execute();
  //$stmt->bindParam(2, $score, PDO::PARAM_INT);
  // $score = 52;
  // $stmt->execute();
  // $score = 44;
  // $stmt->execute();
  // $score = 2;
  // $stmt->execute();

} catch (PDOException $e){
  echo $e->getMessage();
  exit;
}