我想从arduino扫描rfid卡，它应该每天标记一次出勤率，而不是每次扫描卡。
这是用于标记出勤率的php代码：

public function getRFIDAttendanceApi(){
    $rfid_uid = trim($_REQUEST['uid']);
    $sql = "select count(*)as tot from tbl_users where rfid_uid='$rfid_uid'";

    $data = $this->getData($sql);
    if(count($data)>0 && $data[0]['tot']>0){
        $sql = "insert into tbl_attendance set rfid_uid='$rfid_uid'";
        $flag = $this->conn->query($sql);
        if($flag){
            echo "Attendance marked successfully!";
            die;
        } else {
            echo "Sorry! Something unexpected happened!";
            die;    
        }
    } else {
        echo "invalid access";die;
    }

这是mysql中的考勤表，用于重复评分

| att_id | rfid_uid | punch_timestamp     | date       | time     |
+--------+----------+---------------------+------------+----------+
|      1 | 85988145 | 2018-04-21 10:48:51 | 2018-04-21 | 10:48:51 |
|      2 | 85988145 | 2018-04-21 10:48:52 | 2018-04-21 | 10:48:52 |

每天怎么做一次？谢谢。