Php select item from dropdown

?php 
    //get and pass value from 'searchForm.php'
    $id = ''; 
    if(isset( $_GET['id'])) {
        $id = $_GET['id']; 
    }

    //retrieve  dbrecord to the form    
    try{    
        //include db connection
        include "../php/dbconfig.php";
        // Prepare, bind and execute
        $sql = "SELECT crscode,crsname,duration,_deptcode FROM tblcourse WHERE crscode = ?";
        $stmt = $conn -> prepare ($sql);
        $stmt->bind_param("s", $id); 
        $stmt->execute(); 
        $stmt->bind_result($crscode, $crsname,$duration,$_deptcode);
        // Echo
        while ($stmt->fetch()) {
            echo "<pre>";
            echo "Deptcode: $crscode\n";
            echo "Deptname: $crsname\n";
            echo "Deptcode: $duration\n";
            echo "Deptname: $_deptcode\n";

        }
        // Close
        $stmt -> close();
        $conn -> close();    

    }catch(Exception $e){
        //echo "<p>Caught exception: " . $e->getMessage() . "</p>";
    }   

    // Update Function
    function update(){
        $ID = $GLOBALS['id']; // Store the value of varialble $id
        // include db connection
        include "../php/dbconfig.php";
        // Prepare and bind
        $sql = "UPDATE tblcourse SET crsname = ?, duration = ?, _deptcode = ? WHERE crscode = ?";
        $stmt = $conn -> prepare($sql);
        $stmt -> bind_param("ssss",$crsname,$duration,$_deptcode,$ID);
        // Set parameters
        $crsname = trim($_POST['txtcrsname']);
        $duration = trim($_POST['txtduration']);
        $_deptcode = trim($_POST['cbodept']);
        // Execute
        if($stmt -> execute()){
            echo "  
                        window.alert('Record Updated!');
                        window.location='seaCrs.php'; 

                "; 
        }else{
            echo "ERROR: Could not execute query:" . mysqli_error($conn);
        }
        // close 
        $stmt -> close();
        $conn -> close();
    }

    $mssg = "";
    include '../php/functions.php';
    //button update
    if(isset($_POST['btnupdate'])){
        if(empty($_POST['txtcrscode']) || empty($_POST['txtcrsname']) || empty($_POST['txtduration']) || empty($_POST['cbodept'])){
            $GLOBALS['mssg'] = "Please fill up all fields!";
        }else{
            update();   //calling update function
        }
    }

    //btn cancel
    if (isset($_POST['btncancel'])){
        redirect("seaCrs.php");
        echo " window.location='searchDept.php';  ";
    }
?>

<pre>
<title> Update Course 

    .form-con{
        background-color: ;
        width: 100%;
        padding: 10px;
        text-align: left;
    }
    .txtbtn{
        width: 100%;
    }

<br><br><br><br>
<div class="form-con">
    <h2 class="admin-headertitle">UPDATE COURSE</h2>        

        <h3>Course Code:</h3>

        <h3>Course Name:</h3>

        <h3>Duration:</h3>

        <h3>Department: </h3>

             prepare($sql);
                // Execute and fetch
                $stmt -> execute();
                $result = $stmt -> get_result();
                while($row = $result -> fetch_assoc()){
                    //echo "" .$row['deptcode'] ."";
                }
                // Close
                $stmt -> close();
                $conn -> close();*/

            ?> 
             prepare($sql);
                // Execute and fetch
                $stmt -> execute();
                $result = $stmt -> get_result();
                while($row = $result -> fetch_assoc())  { ?>
                 >

        <br><br>

        <br><br>

        <p style="color: rgba(255, 0, 0, 1); font-style: italic"> </p>      

</div>