Db PDO #php

gistfile1.php

<?php
final class Db extends PDO {

	public static $_instance = NULL;
	
	public static function getInstance() {
		
		if (NULL === self::$_instance) {
			self::$_instance = new self();
		}
		
		return self::$_instance;
		
	}
	
	public function __construct() {
		parent::__construct('pgsql:host=127.0.0.1;dbname=foo','user','senha');
		parent::setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
	}
	
	public function fetchRow($query) {
		$sql = parent::query($query);
		return $sql->fetch();
	}
	
	public function fetchOne($query) {
		if ($curr = $this->fetchRow($query))
			return current($curr);
			
		return false;
	}
	
	public function update(array $fields,$where) {
		$set = array();
		foreach ($fields as $f => $v)
			$set[] = "{$f} = {$v}";

		return parent::exec("UPDATE {$this->_table} SET ".join(',',$set)." WHERE {$where}");
	}

	public function insert(array $array) {
		return parent::exec("INSERT INTO {$this->_table}(".join(',',array_keys($array)).") VALUES(".join(',',array_values($array)).")");
	}
		
	public function delete($id) {
		return parent::exec("DELETE FROM {$this->_table} WHERE {$this->_primary} = {$id}");
	}
}