PDO exploite MYSQL (exemple de code)

<?php
    //PDO操作mysql数据库  增删改查
    //1.准备dsn
    $mysql_dsn="mysql:host=localhost;dbname=cz;charset=utf8";
    //2.连接数据库
    try{
        $pdo=new PDO($mysql_dsn,&#39;root&#39;,&#39;123456&#39;);
    }catch(PDOException $e){
        echo $e->getMessage();
    }
    //3.设置错误模式
    $pdo->setAttribute(3,1);
    //查询操作
    $sql="SELECT * FROM user_info WHERE id=:id";
    $stmt=$pdo->prepare($sql);
    // //绑定参数
    $id=1;
    $stmt->bindParam(&#39;id&#39;,$id);
    $bool=$stmt->execute();
    if(!$bool){
        //报错
        var_dump("SQL执行错误");
        exit;
    }else{
        $result=$stmt->fetch(2);
        var_dump($result);
    }
    //删除操作
    $sql="DELETE FROM user_info WHERE id=:id and sex=:sex";
    $stmt=$pdo->prepare($sql);
    $data=array(
        &#39;:id&#39;=>3,
        &#39;:sex&#39;=>&#39;0&#39;
    );
    $bool=$stmt->execute($data);
    //var_dump($bool);
    $result=$stmt->rowCount();
    var_dump($result);
    //修改操作
    $sql="UPDATE user_info SET zname=&#39;jack&#39; WHERE id=:id";
    $stmt=$pdo->prepare($sql);
    $id=5;
    $stmt->bindParam(&#39;:id&#39;,$id);
    $bool=$stmt->execute();
    var_dump($bool);
    $nums=$stmt->rowCount();
    var_dump($nums);

    //添加操作
    $sql="INSERT INTO user_info(id,uid,zname,tel) VALUES(:id,:uid,:zname,:tel)";
    $stmt=$pdo->prepare($sql);
    $data=array(
        &#39;:id&#39;=>2,
        &#39;:uid&#39;=>1,
        &#39;:zname&#39;=>&#39;john&#39;,
        &#39;:tel&#39;=>&#39;11111111111&#39;
    );
    $bool=$stmt->execute($data);
    $nums=$stmt->rowCount();
    var_dump($nums);


?>