<?php
include_once('../../includes/db_connect.php'); 
 if(isset($_POST["lecid2"])){
  $id = trim(mysqli_real_escape_string($con, $_POST["lecid2"]));
   $leccourses=mysqli_fetch_assoc(mysqli_query($con,"SELECT assignedcourses FROM lecturers WHERE id='$id'"))["assignedcourses"];
  if($leccourses!=""){
      $opt="";
      
            $array = explode(',', $leccourses);
            foreach($array AS $courseid){
                $courseid=$courseid;
              
              mysqli_query($con,"INSERT INTO leccourse(lecid,courseid) VALUES('$id','$courseid')");
            }
                $listcat=mysqli_query($con,"SELECT * FROM courses WHERE id NOT IN (SELECT courseid FROM leccourse WHERE lecid='$id') ORDER BY title ASC");
                while($lc=mysqli_fetch_assoc($listcat)){
                    $cid=$lc['id'];
                    
                    $opt.="<option value=".$cid.">".$lc['title']."</option>";
                }
            
   echo $opt; 
   mysqli_query($con,"DELETE FROM leccourse WHERE lecid='$id'");
  }else{
    $listcat=mysqli_query($con,"SELECT * FROM courses ORDER BY title ASC");
        while($lc=mysqli_fetch_assoc($listcat)){ ?>
        <option value="<?php echo $lc['id'] ?>"><?php echo $lc['title'] ?></option>    
      <?php  }
  }
  }
?>