11.27作业-PHP类

1. 把 php公用方法库中的 数据库操作函数， 重写到 Db类中。

class Db{
public $dsn;
public $user;
public $password;

    public $pdo;
    // 类里面的方法，不需要顺序。
    public function __construct($dsn,$user,$password){
        $this->dsn = $dsn;
        $this->user = $user;
        $this->password = $password;
        $this->connect();
    }
    public function connect(){
        $this->pdo = new PDO($this->dsn,$this->user,$this->password);
    }
    public function select($sql){
        $arr = $this->pdo->prepare($sql);
        return $arr;
    }
}
$db = new Db('mysql:host=localhost;dbname=ou','root','root');
$sql = 'select * from user';
$user = $db->pdo->select($sql);
没有懂。第二节也无法看录播。白天还要上班，先交作业。请老师上课讲一下！