php - PDO异常是: "No Database Connection"

Question

我找不到任何使用pdo连接数据库的方法；我尝试了以下语法。

我有php7和pdo支持mysql数据库

ConnectDb 类:

class ConnectDb {
    private $username = "admin";
    private $password = "passw";
    private $connection = NULL;

    protected function __construct($dbname)
    {
        try
        {
            $connection = new PDO("mysql:host=" . "127.0.0.1" . ";dbname=" . $dbname . ";charset=utf8;",$this->username,$this->password,array(PDO::ATTR_PERSISTENT => true));
            $connection->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
        }
        catch (PDOException $exception){
            echo $exception->getMessage();
        }
    }

    protected function getConnection()
    {
        return $this->connection;
    }
}

插入数据类

class InsertDb extends ConnectDb
{
    function __construct($dbname)
    {
        parent::__construct($dbname);
        $this->insert();
    }

    private function insert()
    {
        if ($this->getConnection() !== NULL) {
            $savequer = "INSERT INTO customer (first_name, last_name, email, password) VALUES (?,?,?,?)";
            $savedPdo = $this->getConnection()->prepare($savequer);
            $savedPdo->execute(array($_POST['firstName'], $_POST['lastName'],$_POST['email'], $_POST['password']));
        } else {
            echo "No Database Connection";
        }
    }
}

和我的对象

new InsertDb("tamrin01");

没有数据库连接

Answer 1

在 get_connection 函数中，您返回类成员连接。但在构造函数中，您使用新变量来创建数据库连接。

就像这样。

protected function __construct($dbname)
    {
        try
        {
          //Create a database connection with class member connection. Don't use new variable $connection.
            $this->connection = new PDO("mysql:host=127.0.0.1;dbname=$dbname;charset=utf8;",$this->username,$this->password,array(PDO::ATTR_PERSISTENT => true));
            $this->connection->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
        }
        catch (PDOException $exception){
            echo $exception->getMessage();
        }
    }