Question

in my code below it is not able to recognise the variable $userid, this variable determines the id of the teacher logged in but in the mysqli code it is not able to determine the $userid when I echo it. But it does know the user is logged in by its $userid. So my question is that in the mysqli why is it unable to find the $userid? Please look at comment in mysqli bind_param() setion and this is where the problem is.

Below is the code, both php and mysqli:

Let me state that member.php is the script which contains the $userid info:

    <?php
     session_start();

        include('member.php');

    ...

        function PickSession()
        {

            //Get data from database
            $sessionquery = "
                SELECT s.SessionId, SessionName, s.TeacherId
                FROM Session s
                INNER JOIN Session_Complete sc ON sc.SessionId = s.SessionId
                WHERE
                (ModuleId = ? AND Complete = ? AND s.TeacherId = ?)
                ORDER BY SessionName 
                ";
            $complete = 1;

            global $mysqli;
            $sessionqrystmt=$mysqli->prepare($sessionquery);
            // You only need to call bind_param once
            $sessionqrystmt->bind_param("iii",$moduleId, $complete, $userid);//it doesn't recognse $userid
            // get result and assign variables (prefix with db)
            $sessionqrystmt->execute(); 
            $sessionqrystmt->bind_result($dbSessionId,$dbSessionName,$dbTeacherId);
            $sessionqrystmt->store_result();
            $sessionnum = $sessionqrystmt->num_rows();  

echo $userid; //nothing displayed in this echo
    ...

            if ((isset($username)) && (isset($userid))){ //user is successfully logged in

            include('teachername.php');

    ...

        <?php


        ShowAssessment(); // Show information



            }else{ 

    echo "Please Login to Access this Page | <a href='./teacherlogin.php'>Login</a>";

    }

            ?>

member.php script:

if (isset($_SESSION['teacherid'])) {

      $userid = $_SESSION['teacherid'];

  }

if (isset($_SESSION['teacherusername'])) {

      $username = $_SESSION['teacherusername'];

  }

        ?>

Answer 1

You have not initialised the $userid variable, you have to set the value for binding the variable in query otherwise it will take NULL value for that variable.

$userid = "value";
$sessionqrystmt->bind_param("iii",$moduleId, $complete, $userid);

The $userid variable is not accessible in PickSession(). So the suggestion is either make $userid as global or pass it as parameter in function.