Question

我为我的DB-Connection设置了以下代码，但是我无法从另一个.php文件（在另一个目录中）创建到我的数据库的连接：

我的database.php文件：

<?php

    ini_set('display_errors', 'On');

    public class Database {

        public function __construct() {
            $this->dsn = 'mysql:host=xxx;dbname=xxx';
            $this->username = 'xxx';
            $this->password = 'xxx';   
        }

        public function __construct($dsn, $username, $password) {
            $this->dsn = $dsn;
            $this->username = $username;
            $this->password = $password;
        }

        public function db_connect() {
            try {
                $database = new PDO($this->dsn , $this->username, $this->password);
                return $database;
            } catch(PDOException $e) {
                echo $e->getMessage();
            }
        }

        public function run_query($database, $query){            
            try {
                $result = $database->prepare($query);
                $result->execute();
                return $result;
            } catch (Exception $e) {
                echo $e->getMessage();
                die();
            }
        }

    }

?>

此文件的目录是 currentdirectory /php/database.php。

我正尝试使用以下代码在另一个文件（名为page.php）中实例化数据库连接：

include("php/database.php")
$database = new Database();
$connection = $database->db_connect();
$result = $database->run_query($connection, $query);

此文件的目录是 currentdirectory /page.php。

我一直在寻找一个错误，但是看不出我做错了什么。关于PDO-DB类的其他问题也没有给我带来更多帮助。在此先感谢您的帮助！

Answer 1

public，private，protected用于Class方法和/或属性，不适用于类本身。
您不应该有2个构造函数，或者两个具有相同名称的函数，您将收到致命错误，并且无法重新声明...＆＃39;

请参阅下面的示例它使用dsn组件的私有属性，pdo对象本身和pdo语句您可以在方法中返回这些，以便链接它们。

<?php

class Database {

    private $host;
    private $username;
    private $password;
    private $database;

    private $pdo;
    private $stmt;


    public function __construct($host,$user,$pass,$db) {
        $this->host = $host;
        $this->username = $user;
        $this->password = $pass;
        $this->database = $db;

        $dsn = 'mysql:dbname=' . $this->database .';host=' . $this->host;

        try {

            $this->pdo = new PDO($dsn, $this->username, $this->password);

        } catch (PDOException $e) {
            echo 'Connection failed: ' . $e->getMessage();
        }

    }

    public function query($query){
        $this->stmt = $this->pdo->prepare($query);
        return $this;
    }

    public function getResults(){
        $this->stmt->execute();
        return $this->stmt->fetchAll(PDO::FETCH_ASSOC);
    }

}

用法

// include the file

$db = new Database('localhost','root','','db_name');

print_r($db->query('select * from my_table limit 10')->getResults());

Answer 2

您需要在Content-Type:[multipart/alternative]文件中进行一些更改，因此您的文件代码应为：

database.php

你<?php ini_set('display_errors', 'On'); class Database{ public function __construct(){ $this->dsn = 'mysql:host=xxx;dbname=xxx'; $this->username = 'xxx'; $this->password = 'xxx'; } public function db_connect() { try { $database = new PDO($this->dsn , $this->username, $this->password); return $database; } catch(PDOException $e) { echo $e->getMessage(); } } public function run_query($database, $query){ try { $result = $database->prepare($query); $result->execute(); return $result; } catch (Exception $e) { echo $e->getMessage(); die(); } } } ?>文件代码应为：

page.php

include("php/database.php") $database = new Database(); $connection = $database->db_connect(); $query = "SELECT * FROM table"; $result = $database->run_query($connection, $query);范围仅适用于变量/函数。这不适用于public。

无法从PDO-Database类实例化对象

2 个答案: