連結：$db   = new mysqli("localhost", "root", "mysql", "guanfu_school");
查詢：function query($db,$sql,$type=1){
        $result = $db->query($sql);  
        $data=array();
        while ($tmp=mysqli_fetch_assoc($result)) {
            $data[]=$tmp;
        }
        if($type){
                return $data;
        }else{
            return $data[0];
       }
     }
新增：$db->query("insert into ");
更新：$db->query("update  set ");