在接口被实例化以后的每个方法中return 类本身就可以达到链式操作。

改善了写多行代码执行一次操作的缺点。

下面请看我的代码，若有疑问，请留言给我。

class Instance{

public static $db;

public $mysql=NULL;

private function Connect($host,$user,$pwd,$port=3306){

$this->mysql=mysqli_connect($host,$user,$pwd,$port) or die('Can not Connect Mysql!');

}

private function __construct(){}

private function __clone(){}

public static function getInstance($host,$user,$pwd,$port=3306){

if(!isset(self::$db)){

self::$db = new self;

self::$db->Connect($host,$user,$pwd,$port);

}

return self::$db;

}

}

interface SQL{

/**

* @param string $sql SQL语句

* @return mixed

*/

public function Query($sql);

/**

* @param array $condition 条件

* @return mixed

*/

public function Select($condition=array());

/**

* @param array $condition 条件

* @return mixed

*/

public function Where($condition=array());

/**

* @param array $condition 条件

* @return mixed

*/

public function Group($condition=array());

/**

* @param array $condition 条件

* @return mixed

*/

public function Limit($condition=array());

/**

* @param array $condition 条件

* @return mixed

*/

public function Order($condition=array());

/**

* @return mixed 关闭数据库连接

*/

public function Close();

}

class CoherentModel implements SQL{

private $db; //数据库资源

protected $sql; //SQL语句

protected $result; //结果

public function __construct($db){

if(empty($db->mysql)){

exit('db not connected !');

}

$this->db=$db->mysql;

}

public function Query($sql=''){

$this->sql=$sql;

$this->result=mysqli_query($this->db,$sql);

return $this->result;

}

/**

* @param array $condition 条件

* @return mixed

*/

public function Select($condition=array()){

return $this;

}

/**

* @param array $condition 条件

* @return mixed

*/

public function Where($condition=array()){

return $this;

}

/**

* @param array $condition 条件

* @return mixed

*/

public function Group($condition=array()){

return $this;

}

/**

* @param array $condition 条件

* @return mixed

*/

public function Limit($condition=array()){

return $this;

}

/**

* @param array $condition 条件

* @return mixed

*/

public function Order($condition=array()){

return $this;

}

/**

* @return mixed 关闭数据库连接

*/

public function Close(){

mysqli_close($this->db);

}

}

/**

* 单例模式

*/

$Instance = Instance::getInstance('127.0.0.1','mysql','password');

$Model = new CoherentModel($Instance::$db);

/**

* 链式操作

*/

$Model->Where()->Group()->limit()->Select();