下面是我到目前为止提出的数据库连接类,但我将通过扩展 PDO 类本身来改进它,
<?php
class database
{
protected $connection = null;
#make a connection
public function __construct($hostname,$dbname,$username,$password)
{
try
{
# MySQL with PDO_MYSQL
$this->connection = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password);
$this->connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e)
{
$this->connection = null;
die($e->getMessage());
}
}
#get the number of rows in a result
public function num_rows($query)
{
# create a prepared statement
$stmt = $this->connection->prepare($query);
if($stmt)
{
# execute query
$stmt->execute();
return $stmt->rowCount();
}
else
{
return self::get_error();
}
}
#display error
public function get_error()
{
$this->connection->errorInfo();
}
# closes the database connection when object is destroyed.
public function __destruct()
{
$this->connection = null;
}
}
?>
扩展类,
class database extends PDO
{
#make a connection
public function __construct($hostname,$dbname,$username,$password)
{
parent::__construct($hostname,$dbname,$username,$password);
try
{
$this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e)
{
die($e->getMessage());
}
}
#get the number of rows in a result
public function num_rows($query)
{
# create a prepared statement
$stmt = parent::prepare($query);
if($stmt)
{
# execute query
$stmt->execute();
return $stmt->rowCount();
}
else
{
return self::get_error();
}
}
#display error
public function get_error()
{
$this->connection->errorInfo();
}
# closes the database connection when object is destroyed.
public function __destruct()
{
$this->connection = null;
}
}
这就是我实例化类的方式,
# the host used to access DB
define('DB_HOST', 'localhost');
# the username used to access DB
define('DB_USER', 'root');
# the password for the username
define('DB_PASS', 'xxx');
# the name of your databse
define('DB_NAME', 'db_2011');
include 'class_database.php';
$connection = new database(DB_HOST,DB_NAME,DB_USER,DB_PASS);
$sql = "
SELECT *
FROM root_contacts_cfm
ORDER BY cnt_id DESC
";
$connection->num_rows($sql);
但是当我调用这个扩展的 pdo 类时出现错误,
警告:PDO::__construct() 期望参数 4 是数组,字符串在 C:\wamp\www\xx\class_database.php 的第 xx 行
致命错误:在第 xx 行的 C:\wamp\www\xx\class_database.php 中的非对象上调用成员函数 setAttribute()
我在网上做了一些研究,我发现了扩展pdo的基本结构,但我不明白......
class myPDO extends PDO
{
public function __construct($dsn,
$username=null,
$password=null,
$driver_options=null)
{
parent::__construct($dsn, $username, $password, $driver_options);
}
public function query($query)
{
$result = parent::query($query);
// do other stuff you want to do here, then...
return($result);
}
}
$ds
n 变量有什么用?如何将我的$hostname
变量传递给扩展的 pdo 类?
另一个问题:如何在扩展的 pdo 类中创建一种显示错误的方法?如何关闭扩展 pdo 类中的连接?
从 mysqli 迁移到 pdo 太难了!
谢谢。