Notice: Undefined index: email in F:\xamp\htdocs\firse\addTeacher.php on line 5

i am not able to insert email to the database but userid and password have inserted


    $userid= trim($_POST["userid"]);
    $password = trim($_POST["password"]);
    $con = mysqli_connect("localhost", "root", "", "tryagain");
    if($con === false)
        die("ERROR: Could not connect. " . mysqli_connect_error());
    $query="SELECT userid FROM teacherid WHERE userid='$userid'";

    if($numrows > 0)
            echo "userid already exist in teacherid relation";
        $addquery="INSERT into teacherid(userid,password,email)values('$userid','$password','$email')";
            echo "iserted successfully";