myDBH.php

<?php
class myDBH {
  private $db_info = array("host" => "localhost", "dbname" => "myDB", "username" => "myDB_user", "password" => "myDB_password");
  private $dbh;
 
  public static $instance = NULL;
 
  public function __construct(array $db_info = null) {
    if(isset($db_info)) {
      foreach($db_info as $key_name => $key_value) {
        if(!in_array($key_name, array("host", "db_name", "username", "password") || empty($key_value))) {
          throw new Exception("Invalid key passed!");
        }
        $this->db_info = $db_info;
      }
    }
    $this->dbh = new PDO("mysql:host={$this->db_info['host']};dbname={$this->db_info['db_name']}", $this->db_info['username'], $this->db_info['password'], array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));
    $this->dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $this->dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, true);
    $this->dbh->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
  }
 
  public static function getInstance() {
    if(!isset(self::$instance)) {
      self::$instance = new myDBH();
    }
    return self::$instance;
  }
 
  public function fetch_rows($sql) {
    $rst = $this->dbh->query($sql);
    return $rst->fetchAll();
  }
 
  public function fetch_row($sql) {
    $rst = $this->dbh->query($sql);
    return $rst->fetch();
  }
}
?>