PHP Data Objects

はじめに

PHP Data Objects (PDO) 拡張モジュールは、 PHP の中からデータベースにアクセスするための軽量で高性能な インターフェイスを定義します。 PDO インターフェイスを実装する各データベースドライバは、 正規表現関数のようなデータベース固有の機能を提供することができます。 PDO 拡張モジュールによりそのデータベースの全てのデータベース関数を 実行できるわけではないことに注意してください。 データベースサーバーにアクセスするには、 データベース固有の PDO ドライバ を使用する必要があります。

PDO は、データアクセスの抽象化レイヤを提供します。 つまり、使用しているデータベースが何であるかにかかわらず、同じ 関数を使用してクエリの発行やデータの取得が行えるということです。 PDO は、データベースの抽象化を行うのでは ありません。つまり、SQL を書き直したり 存在しない機能をエミュレートしたりはしないということです。 もしそのような機能が必要なら、全体を網羅する (full-blown) 別の抽象化レイヤを使用すべきです。

PDO は PHP 本体にバンドルされています。

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User Contributed Notes 5 notes

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123
djlopez at gmx dot de
19 years ago
Please note this:

Won't work:
$sth = $dbh->prepare('SELECT name, colour, calories FROM ?  WHERE calories < ?');

THIS WORKS!
$sth = $dbh->prepare('SELECT name, colour, calories FROM fruit WHERE calories < ?');

The parameter cannot be applied on table names!!
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5
wiserufferto at gmail dot com
5 years ago
This is a little late... but I'm old and slow.......
Regarding Extending PDOStatement and PDO I found that sending the PDOExtended class by reference helps:
    In the constructor after parent::__construct() :
$this->setAttribute(\PDO::ATTR_STATEMENT_CLASS,array('PDOStatementExtended', [&$this]));}

And in 
class PDOStatementExtended extends \PDOStatement
{
  
  protected function __construct
  (
    \PDO &$PDO,
   )
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11
pokojny at radlight dot com
19 years ago
I wanted to extend PDO class to store statistics of DB usage, and I faced some problems. I wanted to count number of created statements and number of their executings. So PDOStatement should have link to PDO that created it and stores the statistical info. The problem was that I didn't knew how PDO creates PDOStatement (constructor parameters and so on), so I have created these two classes:

<?php
/**
 * PHP Document Object plus
 * 
 * PHP Document Object plus is library with functionality of PDO, entirely written
 * in PHP, so that developer can easily extend it's classes with specific functionality,
 * such as providing database usage statistics implemented in v1.0b
 * 
 * @author Peter Pokojny
 * @license http://opensource.org/licenses/gpl-license.php GNU Public License
 */
    class PDOp {
        protected $PDO;
        public $numExecutes;
        public $numStatements;
        public function __construct($dsn, $user=NULL, $pass=NULL, $driver_options=NULL) {
            $this->PDO = new PDO($dsn, $user, $pass, $driver_options);
            $this->numExecutes = 0;
            $this->numStatements = 0;
        }
        public function __call($func, $args) {
            return call_user_func_array(array(&$this->PDO, $func), $args);
        }
        public function prepare() {
            $this->numStatements++;
            
            $args = func_get_args();
            $PDOS = call_user_func_array(array(&$this->PDO, 'prepare'), $args);
            
            return new PDOpStatement($this, $PDOS);
        }
        public function query() {
            $this->numExecutes++;
            $this->numStatements++;
            
            $args = func_get_args();
            $PDOS = call_user_func_array(array(&$this->PDO, 'query'), $args);
            
            return new PDOpStatement($this, $PDOS);
        }
        public function exec() {
            $this->numExecutes++;
            
            $args = func_get_args();
            return call_user_func_array(array(&$this->PDO, 'exec'), $args);
        }
    }
    class PDOpStatement implements IteratorAggregate {
        protected $PDOS;
        protected $PDOp;
        public function __construct($PDOp, $PDOS) {
            $this->PDOp = $PDOp;
            $this->PDOS = $PDOS;
        }
        public function __call($func, $args) {
            return call_user_func_array(array(&$this->PDOS, $func), $args);
        }
        public function bindColumn($column, &$param, $type=NULL) {
            if ($type === NULL)
                $this->PDOS->bindColumn($column, $param);
            else
                $this->PDOS->bindColumn($column, $param, $type);
        }
        public function bindParam($column, &$param, $type=NULL) {
            if ($type === NULL)
                $this->PDOS->bindParam($column, $param);
            else
                $this->PDOS->bindParam($column, $param, $type);
        }
        public function execute() {
            $this->PDOp->numExecutes++;
            $args = func_get_args();
            return call_user_func_array(array(&$this->PDOS, 'execute'), $args);
        }
        public function __get($property) {
            return $this->PDOS->$property;
        }
        public function getIterator() {
            return $this->PDOS;
        }
   }
?>

Classes have properties with original PDO and PDOStatement objects, which are providing the functionality to PDOp and PDOpStatement.
From outside, PDOp and PDOpStatement look like PDO and PDOStatement, but also are providing wanted info.
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0
dougwilbourne at gmail dot com
1 year ago
Now that current versions of MySQL are forcing users to authenticate with caching_sha2_password instead of mysql_native_driver, I wanted to get PDO to send passwords that way.  I think the only way to do it is to make the connection over SSL. Setting up your web server and database server for SSL is way beyond the scope of this note, but after you do, remember that you will need to add an options array as the last argument in your PDO connection arguments.  At a minimum, you will need to supply the server certificate.  In a development environment with a self-signed server certificate, you will also want to bypass verification that your server certificate is 'real'.  So your options array would look like this

$opts = [ PDO::MYSQL_ATTR_SSL_CA => $server_cert_file_path, PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT => false];

Hope it helps!
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-2
www.navin.biz
20 years ago
Below is an example of extending PDO & PDOStatement classes:

<?php

class Database extends PDO
{
    function __construct()
    {
        parent::__construct('mysql:dbname=test;host=localhost', 'root', '');
        $this->setAttribute(PDO::ATTR_STATEMENT_CLASS, array('DBStatement', array($this)));
    }
}

class DBStatement extends PDOStatement
{
    public $dbh;

    protected function __construct($dbh)
    {
        $this->dbh = $dbh;
        $this->setFetchMode(PDO::FETCH_OBJ);
    }
    
    public function foundRows()
    {
        $rows = $this->dbh->prepare('SELECT found_rows() AS rows', array(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE));
        $rows->execute();
        $rowsCount = $rows->fetch(PDO::FETCH_OBJ)->rows;
        $rows->closeCursor();
        return $rowsCount;
    }
}

?>
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