<?php
class Database {
    private $_db;
    static $_instance;
    final private function __construct($dbname,$user='root',$password='',$port='3306') {
        $conStr = "dbname=".$dbname." user=".$user." password=".$password." port=".$port;
        $this->_db = pg_connect($conStr);
    }
    private __clone() {};
    public static function getInstance($dbname,$user='root',$password='',$port='3306') {
        if( ! (self::$_instance instanceof self) ) {
            self::$_instance = new self($dbname,$user='root',$password='',$port='3306');
        }
        return self::$_instance;
    }
    public function query($sql) {
        return pg_query($this->_db, $sql);
    }
}
?>