databasehelper.php

<?php

class DatabaseException extends Exception
{
    const UNKNOWN = 0;
    const BAD_CONNECT = 1;

    public function __construct($message, $code = 0, Exception $previous = null)
    {
        parent::__construct($message, $code, $previous);
    }
}

class DatabaseHelper
{
    private $conn = null;

    const DEFAULT_HOST = 'localhost';
    const DEFAULT_PORT = 5432;
    const DEFAULT_DATABASE = 'database';
    const DEFAULT_USER = 'user';
    const DEFAULT_PASSWORD = 'password';

    private $host;
    private $port;
    private $database;
    private $user;
    private $password;

    private $DSN;

    private static $gdbh = null;

    function __construct($host = DatabaseHelper::DEFAULT_HOST, $port = DatabaseHelper::DEFAULT_PORT,
        $database = DatabaseHelper::DEFAULT_DATABASE, $user = DatabaseHelper::DEFAULT_USER, $use_password = TRUE,
        $password = DatabaseHelper::DEFAULT_PASSWORD)
    {
        $this->host = $host;
        $this->port = $port;
        $this->database = $database;
        $this->user = $user;
        $this->password = $password;

        if ($use_password)
        {
            $this->DSN = sprintf("pgsql:host=%s;port=%d;dbname=%s;user=%s;password=%s",
                $this->host, $this->port, $this->database, $this->user, $this->password);
        }
        else
        {
            $this->DSN = sprintf("pgsql:host=%s;port=%d;dbname=%s;user=%s",
                $this->host, $this->port, $this->database, $this->user);
        }
    }

    function __destruct()
    {
        $this->close();
    }

    public function connect()
    {
        try
        {
            $this->conn = new PDO($this->DSN);
        }
        catch (PDOException $e)
        {
            $error_arr = $pstmt->errorInfo();
            $error_str = "Could not connect to server. "
                . "SQLSTATE code: " . $error_arr[0]
                . ", Driver code: " . $error_arr[1]
                . ", Message: " . $error_arr[2];

            throw new DatabaseException($error_str, DatabaseException::BAD_CONNECT, $e);
        }
    }

    public function close()
    {
        $this->conn = null;
    }

    public function getConnection()
    {
        if ($this->conn == null)
        {
            $this->connect();
        }

        return $this->conn;
    }

    public static function getInstance()
    {
        if (DatabaseHelper::$gdbh == null)
        {
            DatabaseHelper::$gdbh = new DatabaseHelper();
        }

        return DatabaseHelper::$gdbh;
    }

}

?>