1.添加页面
<h1>添加数据</h1>
<form action="chuli.php" method="post">
   <div>代号：<input type="text" name="code" /></div>
   <div>名称：<input type="text" name="name" /></div>
   <input type="submit" value="添加" />
</form>

2.处理页面
（1）造PDO对象
$dsn = "mysql:dbname=mydb;host=localhost";
$pdo = new PDO($dsn,"root","123");

（2）预处理语句
$sql = "insert into nation values(:code,:name)";
$stm = $pdo->prepare($sql);

（3）执行
$stm->execute($_POST);