<?php

/*
	mysql資料庫操作類
	0、實現了單例模式
	1、該類一例項化，就可以自動連線上mysql資料庫
	2、該類可以單獨去設定要使用的連線編碼
	3、該類可以單獨設定要使用的資料庫
	4、可以主動關閉資料庫連線
	5、完成了DML、DQL操作的簡單封裝
	6、實現了簡單的sql執行錯誤處理
*/

class MySQLDB{
	private $link = null;	#用於儲存連線資料庫成功後的“資源”
	protected $host;
	protected $port;
	protected $user;
	protected $password;
	protected $charset;
	protected $dbname;

	/**
		單例實現
	//*/
	private static $instance = null;	#用於儲存該類的唯一例項
	private function __clone(){}	#禁止該類的例項物件進行克隆複製物件
	#對外提供一個建立該類例項的方法
	public static function getInstance($config){
		if(!(static::$instance instanceof self)){
			static::$instance = new self($config);
		}
		return static::$instance;
	}
	#實現單例的基礎：私有化該類的構造方法
	private function __construct($config){
		$this->host = isset($config['host'])?$config['host']:'localhost';
		$this->port = isset($config['port'])?$config['port']:'3306';
		$this->user = isset($config['user'])?$config['user']:'root';
		$this->password = isset($config['password'])?$config['password']:'root';
		$this->charset = isset($config['charset'])?$config['charset']:'utf8';
		$this->dbname = isset($config['dbname'])?$config['dbname']:'db_mvc';

		$this->link = @mysql_connect(
			"{$this->host}:{$thi->port}","{$this->user}","$this->password")
			or die(連線失敗！);

		$this->selectDB($this->dbname);
		$this->setCharset($this->charset);
	} 

	public function setCharset($charset){#1設定連線環境字元編碼
		$sql = "set names {$charset}";
		$this->query($sql);
	}
	
	public function selectDB($dbname){#2選擇要操作的資料庫
		$sql = "use {$dbname}";
		$this->query($sql);
	}

	public function closeDB(){#3關閉資料庫連線
		if(isset($this->link)){
			mysql_query($this->link);
		}
	}

	public function execute($sql){#增刪改
		$this->query($sql);
		return true;
	}

	public function getData($sql){#返回結果是一個標量值
		$result = $this->query($sql);
		$num = mysql_fetch_array($result);
		mysql_free_result($result);
		return $num[0];
	}

	public function getRow($sql){#返回結果是一個一維陣列
		$result = $this->query($sql);
		$row = mysql_fetch_array($result);
		mysql_free_result($result);
		return $row;
	}
	
	public function getRows($sql){#返回結果是一個二維陣列
		$result = $this->query($sql);
		$arr = array();
		while($row = mysql_fetch_array($result)){
			$arr[] = $row;
		}

		mysql_free_result($result);
		return $arr;
	}

	private function query($sql){#錯誤處理並返回一個結果集
		$result = mysql_query($sql);
		if($result === false){
			echo "程式碼執行錯誤！請參考如下提示：";
			echo "<br />錯誤代號：".mysql_errno();
			echo "<br />錯誤內容：".mysql_error();
			echo "<br />錯誤程式碼：".$sql;

			die();
		}
		return $result;
	}
}

?>