PHP MYSQL 每天一次的出勤限制

Question

I am Beginner in php and i am making the project on attendance system but i don't know how to code for single-day attendance for the student once in a day. I didn't get the appropriate result. Thanks in advance.

<?php
include 'config.php';

    if($_SESSION['user']==true){
        if(isset($_POST['submit'])){

              $sql= ("INSERT INTO `student_attendence`(`Student_id`,`Date`,`Attendence`) VALUES ('".$_SESSION['user']."','$date','$attendence') ");

                if(count($error)==0){
                    if(!mysqli_query($conn,$sql)){
                        echo "Error ".mysqli_error($conn);

                    }
                    else{
                        header("location:studentlogin.php");
                    }
                }        
        }
    }   
    else{
        header("location:studentlogin.php");
    }

?>

Answer 1

You have to increase one more attribute in DB table which is date .
So whenever you insert a new attendence insert today's date also.
Always check for today's date must not present in DB before inserting the attendence.
So while inserting the attendence in DB, you must have to check first -

If today's date is already present in DB
   true : display message(today's attendence has already taken).

   false: save the attendence in DB.

Note - MySQL's default DATE format is YYYY-MM-DD .

This is the quick method you can impliment.