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La clase PDO

(PHP 5 >= 5.1.0, PECL pdo >= 0.1.0)

Introducción

Representa una conexión entre PHP y un servidor de bases de datos.

Sinopsis de la Clase

PDO {
public __construct ( string $dsn [, string $username [, string $password [, array $options ]]] )
public bool beginTransaction ( void )
public bool commit ( void )
public mixed errorCode ( void )
public array errorInfo ( void )
public int exec ( string $statement )
public mixed getAttribute ( int $attribute )
public static array getAvailableDrivers ( void )
public bool inTransaction ( void )
public string lastInsertId ([ string $name = NULL ] )
public PDOStatement prepare ( string $statement [, array $driver_options = array() ] )
public PDOStatement query ( string $statement )
public string quote ( string $string [, int $parameter_type = PDO::PARAM_STR ] )
public bool rollBack ( void )
public bool setAttribute ( int $attribute , mixed $value )
}

Tabla de contenidos

  • PDO::beginTransaction — Inicia una transacción
  • PDO::commit — Consigna una transacción
  • PDO::__construct — Crea una instancia de PDO que representa una conexión a una base de datos
  • PDO::errorCode — Obtiene un SQLSTATE asociado con la última operación en el manejador de la base de datos
  • PDO::errorInfo — Obtiene información extendida del error asociado con la última operación del manejador de la base de datos
  • PDO::exec — Ejecuta una sentencia SQL y devuelve el número de filas afectadas
  • PDO::getAttribute — Devuelve un atributo de la conexión a la base de datos
  • PDO::getAvailableDrivers — Devuelve un array con los controladores de PDO disponibles
  • PDO::inTransaction — Comprueba si una transacción está activa
  • PDO::lastInsertId — Devuelve el ID de la última fila o secuencia insertada
  • PDO::prepare — Prepara una sentencia para su ejecución y devuelve un objeto sentencia
  • PDO::query — Ejecuta una sentencia SQL, devolviendo un conjunto de resultados como un objeto PDOStatement
  • PDO::quote — Entrecomilla una cadena de caracteres para usarla en una consulta
  • PDO::rollBack — Revierte una transacción
  • PDO::setAttribute — Establece un atributo
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User Contributed Notes 6 notes

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11
williambarry007 at gmail dot com
2 years ago
PDO and Dependency Injection

Dependency injection is good for testing.  But for anyone wanting various data mapper objects to have a database connection, dependency injection can make other model code very messy because database objects have to be instantiated all over the place and given to the data mapper objects.

The code below is a good way to maintain dependency injection while keeping clean and minimal model code.

<?php

class DataMapper
{
    public static
$db;
   
    public static function
init($db)
    {
       
self::$db = $db;
    }
}

class
VendorMapper extends DataMapper
{
    public static function
add($vendor)
    {
       
$st = self::$db->prepare(
           
"insert into vendors set
            first_name = :first_name,
            last_name = :last_name"
       
);
       
$st->execute(array(
           
':first_name' => $vendor->first_name,
           
':last_name' => $vendor->last_name
       
));
    }
}

// In your bootstrap
$db = new PDO(...);
DataMapper::init($db);

// In your model logic
$vendor = new Vendor('John', 'Doe');
VendorMapper::add($vendor);

?>
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5
thz at plista dot com
1 year ago
Starting with PHP 5.4 you are unable to use persistent connections when you have your own database class derived from the native PDO class. If your code uses this combination, you will encounter segmentation faults during the cleanup of the PHP process.
You can still use _either_ a derived PDO class _or_ persistent connections.

For more information, please see this bug report: https://bugs.php.net/bug.php?id=63176
up
6
schizo_mind at hotmail dot com
6 years ago
<?php
class PDOConfig extends PDO {
   
    private
$engine;
    private
$host;
    private
$database;
    private
$user;
    private
$pass;
   
    public function
__construct(){
       
$this->engine = 'mysql';
       
$this->host = 'localhost';
       
$this->database = '';
       
$this->user = 'root';
       
$this->pass = '';
       
$dns = $this->engine.':dbname='.$this->database.";host=".$this->host;
       
parent::__construct( $dns, $this->user, $this->pass );
    }
}
?>
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3
anrdaemon at freemail dot ru
5 years ago
Keep in mind, you MUST NOT use 'root' user in your applications, unless your application designed to do a database maintenance.

And storing username/password inside class is not a very good idea for production code. You would need to edit the actual working code to change settings, which is bad.
up
2
Megaloman
5 years ago
"And storing username/password inside class is not a very good idea for production code."

Good idea is to store database connection settings in *.ini files but you have to restrict access to them. For example this way:

my_setting.ini:
[database]
driver = mysql
host = localhost
;port = 3306
schema = db_schema
username = user
password = secret

Database connection:
<?php
class MyPDO extends PDO
{
    public function
__construct($file = 'my_setting.ini')
    {
        if (!
$settings = parse_ini_file($file, TRUE)) throw new exception('Unable to open ' . $file . '.');
       
       
$dns = $settings['database']['driver'] .
       
':host=' . $settings['database']['host'] .
        ((!empty(
$settings['database']['port'])) ? (';port=' . $settings['database']['port']) : '') .
       
';dbname=' . $settings['database']['schema'];
       
       
parent::__construct($dns, $settings['database']['username'], $settings['database']['password']);
    }
}
?>

Database connection parameters are accessible via human readable ini file for those who screams even if they see one PHP/HTML/any_other command.
up
-2
kcleung at kcleung dot no-ip dot org
4 years ago
Here is an singleton PDO example:

###### config.ini ######
db_driver=mysql
db_user=root
db_password=924892xp

[dsn]
host=localhost
port=3306
dbname=localhost

[db_options]
PDO::MYSQL_ATTR_INIT_COMMAND=set names utf8

[db_attributes]
ATTR_ERRMODE=ERRMODE_EXCEPTION
############

<?php class Database {
    private static
$link = null ;

    private static function
getLink ( ) {
        if (
self :: $link ) {
            return
self :: $link ;
        }

       
$ini = _BASE_DIR . "config.ini" ;
       
$parse = parse_ini_file ( $ini , true ) ;

       
$driver = $parse [ "db_driver" ] ;
       
$dsn = "${driver}:" ;
       
$user = $parse [ "db_user" ] ;
       
$password = $parse [ "db_password" ] ;
       
$options = $parse [ "db_options" ] ;
       
$attributes = $parse [ "db_attributes" ] ;

        foreach (
$parse [ "dsn" ] as $k => $v ) {
           
$dsn .= "${k}=${v};" ;
        }

       
self :: $link = new PDO ( $dsn, $user, $password, $options ) ;

        foreach (
$attributes as $k => $v ) {
           
self :: $link -> setAttribute ( constant ( "PDO::{$k}" )
                ,
constant ( "PDO::{$v}" ) ) ;
        }

        return
self :: $link ;
    }

    public static function
__callStatic ( $name, $args ) {
       
$callback = array ( self :: getLink ( ), $name ) ;
        return
call_user_func_array ( $callback , $args ) ;
    }
}
?>

<?php // examples
$stmt = Database :: prepare ( "SELECT 'something' ;" ) ;
$stmt -> execute ( ) ;
var_dump ( $stmt -> fetchAll ( ) ) ;
$stmt -> closeCursor ( ) ;
?>
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