Php 简单PDO包装器不工作

我正在尝试这个包装器，不管怎样，当我在index.php文件中var_dump（$row）时，我总是得到“boolean false”

这是我的db类：

<?php
// database.php
class DB {
protected $_connection = array();  // to map the connection
protected $_dbh;                   // property which keeps the database handler
protected $_database;              // property to keep the database name
protected $_table;                 // property to keep the table name
protected $_query;                 // property to keep a query statement

public function __construct() {

    // require the database configurations as an array from config.php
    $this->_connection = require_once 'config.php';
    // define which database driver to use (mysql?) and extract the values as 
    // variables
    extract($this->_connection['connection']['mysql']);

    // make the database and table name available to the class
    $this->_database = $database;
    $this->_table    = $table_name;

    // Check for PDO driver and create the connection to the database.
    try {
        $this->_dbh = new PDO($driver.":host=".$host, $username, $password);
    } catch (PDOException $e) {
        die ('Connection failed: ' . $e->getMessage());
    }
}

public function input_query($query) {
    $this->_query = $this->_dbh->prepare($query);
    return $this;
}

public function execute() {
    return $this->_query->execute();
}

public function single() {
    $this->execute();
    return $this->_query->fetch();
}

public function result_set() {
    $this->execute();
    return $this->fetchAll();
}    
}

但是var\u dump（$r）总是返回布尔值false，有时当我尝试使用代码执行不同操作时，会得到“调用未定义的方法DB:：single（）”，或“非对象上的方法”类消息

有人能帮我解决这个问题吗

---

非常感谢。问候。

好的，现在它工作得很好。代码如下：

<?php // database.php
class DB extends PDO {

    protected $_connection = array();         // to map the connection

    protected $_dbh;                        // property which keeps the database handler

    protected $_database;                   // property to keep the database name

    protected $_table;                      // property to keep the table name

    protected $_query;                       // property to keep a query statement

    public function __construct() {

        // require the database configurations as an array from config.php
        $this->_connection = require_once 'config.php';
        // define which database driver to use (mysql?) and extract the values as variables
        extract($this->_connection['connection']['mysql']);

        // make the database and table name available to the class
        $this->_database = $database;
        $this->_table    = $table_name;

        // build the dsn string value for the PDO connection
        $dsn = $driver.":host=".$host.";dbname=".$database;

        // Check for PDO driver and create the connection to the database.
        try {
            parent::__construct($dsn, $username, $password, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
        } catch (PDOException $e) {
            die ('Connection failed: ' . $e->getMessage());
        }
    }

    public function input_query($query) {
        $this->_query = parent::prepare($query);
        return $this;
    }

    public function execute() {
        return $this->_query->execute();
    }

    public function single() {
        $this->execute();
        return $this->_query->fetch();
    }

    public function result_set() {
        $this->execute();
        return $this->_query->fetchAll();
    }
}

---

您似乎没有选择数据库，因此可能是您的查询出错了。添加
数组（PDO:：ATTR_ERRMODE=>PDO:：ERRMODE_EXCEPTION）
作为
new PDO（）
构造函数的最后一个参数，以便更好地调试。为了我的理智起见，如果没有其他内容，请大家停止为PDO编写包装器类。它不需要OO包装，它已经是OO了。如果你想要额外的功能/sugar方法，扩展它。尝试用Try/catch包装execute并检查错误代码@kevinmajor1@kevinmajor1，放松点，伙计们。我在学这些东西。没必要粗鲁。建议一个更好的解决方案与提出一个更有经验的程序员比提出问题而不是侮辱的程序员有区别。如果你讨厌帮助新手，就不要帮助他们。
<?php
// index.php 
require_once 'database.php';

$db = new DB();
var_dump($db);

object(DB)[1]
  public '_connection' => 
    array (size=1)
      'connection' => 
        array (size=4)
          'sqlite' => 
            array (size=3)
              ...
          'mysql' => 
            array (size=6)
              ...
          'pgsql' => 
            array (size=6)
              ...
          'sqlsrv' => 
            array (size=6)
              ...
  protected '_dbh' => 
    object(PDO)[2]
  protected '_database' => string 'pagination_demo' (length=15)
  protected '_table' => string 'names' (length=5)
  protected '_query' => null

<?php // database.php
class DB extends PDO {

    protected $_connection = array();         // to map the connection

    protected $_dbh;                        // property which keeps the database handler

    protected $_database;                   // property to keep the database name

    protected $_table;                      // property to keep the table name

    protected $_query;                       // property to keep a query statement

    public function __construct() {

        // require the database configurations as an array from config.php
        $this->_connection = require_once 'config.php';
        // define which database driver to use (mysql?) and extract the values as variables
        extract($this->_connection['connection']['mysql']);

        // make the database and table name available to the class
        $this->_database = $database;
        $this->_table    = $table_name;

        // build the dsn string value for the PDO connection
        $dsn = $driver.":host=".$host.";dbname=".$database;

        // Check for PDO driver and create the connection to the database.
        try {
            parent::__construct($dsn, $username, $password, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
        } catch (PDOException $e) {
            die ('Connection failed: ' . $e->getMessage());
        }
    }

    public function input_query($query) {
        $this->_query = parent::prepare($query);
        return $this;
    }

    public function execute() {
        return $this->_query->execute();
    }

    public function single() {
        $this->execute();
        return $this->_query->fetch();
    }

    public function result_set() {
        $this->execute();
        return $this->_query->fetchAll();
    }
}

<?php
require_once 'database.php';

$db = new DB();

$db->input_query("SELECT `name` FROM `names`");

try {
    $r = $db->result_set();
} catch (PDOException $e) {
    die ($e->getMessage());
}
var_dump($r);