面向对象来实现数据库操作

/*一个文件MySQLDB.class.php中包含了一个类来连接数据库、
执行语句的方法、
将查询到的结果集通过数组返回的方法。

*/
host = isset($config['host']) ? $config['host'] : 'localhost';
		$this->port = isset($config['port']) ? $config['port'] : '3306';
		$this->username = isset($config['username']) ? $config['username'] : 'root';
		$this->password = isset($config['password']) ? $config['password'] : 'forlove123';
		$this->charset = isset($config['charset']) ? $config['charset'] : 'utf8';
		$this->dbname = isset($config['dbname']) ? $config['dbname'] : 'newphp';
		
		//连接数据库的函数调用,没件事独立使用
		$this->connect();
		//设定连接编码
		$this->setCharset($this->charset);
		//选定数据库
		$this->selectDb($this->dbname);
	}
	public static function getInstance($config){
		if(!isset(self::$link)){
			self::$link = new self($config);		//参数问题
		}
		return self::$link;
	} 
	//禁止克隆
	private function __clone(){}
	public function connect(){
		$this->resource = mysql_connect("$this->host:$this->port", "$this->username", "$this->password") or die("连接数据库失败");
	}
	public function setCharset($charset){
		//mysql_set_charset($charset, self::$link);
		mysql_query("set names $charset");	//设置编码失败易于显示错误
	}
	public function selectDb($dbname){
		//mysql_select_db($dbname, self::$link);
		mysql_query("use $dbname");		//选择数据库失败易于显示错误
	}
	/*
	功能执行sql语句
	返回，失败直接结束，成功则返回执行结果
	*/
	public function query($sql){
		if(!$result = mysql_query($sql, $this->resource)){
			echo	"
执行语句失败";
			echo	"
执行失败语句为：".$sql;
			echo	"
出错信息为：".mysql_error();
			echo	"
错误代号为：".mysql_errno();
			die();
		}
		return $result;
	}
	/*
	执行select语句返回二维数组
	参数:$sql 字符串类型 select语句
	*/
	public function getAll($sql){
		$result = $this->query($sql);
		$arr = array();
		while( $rec = mysql_fetch_assoc( $result )){
			$arr[] = $rec;
		}
		return $arr;
	}
	public function getRow($sql){
		$result = $this->query($sql);
		while( $rec = mysql_fetch_assoc( $result )){	//返回下标为字段名的下标
			//如果取得了一行数据
			return $rec;
		}
		return false;
	}
	public function getOne($sql){
		$result = $this->query($sql);			//结果集为0行也不会判断为false, 它是资源
		$rec = mysql_fetch_row($result);	//返回下标为数字的数组，且下标一定为0,1,2,3
		if($rec == false){
			return false;
		}
		return $rec[0];
	}
}
/*
测试文件:MysqlDb_use.php
*/
 'localhost',
	'port' => '3306',
	'username' => 'root',
	'password' => 'forlove123',
	'charset' => 'utf8',
	'dbname' => 'newphp'
	);        //设置连接数据库信息
$link = MySQLDB::getInstance( $config );    //单例话一个对象那个
//var_dump($link);

//任务1：插入数据:        
$sql = "insert into money(zhanghu, cunkuan) values ('test3', 10000)";
if( $link ->query($sql) )
	echo	"执行成功";
//任务2获取账户所有信息
$sql = "select * from money";
$result = $link->getAll($sql);
echo	"
";
//print_r($result);
echo	"";
	foreach ($result as $rows){
		echo	"";
			foreach ($rows as $key => $value){
				echo	"";
			}
		echo	"";
	}
echo	"
$value
";
echo	"
";
//任务3：获取某个账户信息（一行数据）：
$sql = "select * from  money where id = 1";
$result = $link->getRow($sql);	//得到一维数组
if($result){
	echo	"
账户ID：".$result['id'];
	echo	"
账户名：".$result['zhanghu'];
	echo	"
存款为：".$result['cunkuan'];
}
else 
	echo	"
账户不存在！！！";

//获取银行的存款总和
$sql = "select sum(cunkuan) as s from money ";
$result = $link->getOne($sql);
if($result)
	echo	"
总存款为：".$result;
else
	echo	"";
?>

测试结果为：