Save Logged in user data in Session in ASP.Net MVC

I have created my first application using MVC in ASP.NET and C#.

On the controller.cs I use code below for recognize the user (tUser) whether registered or not on table database tUser.

If the user exists on the table tUser I set the session.

I don't have problem if the user registered has associated only one code (tCode), e.g.

+-----------------+--------+
| tUser           | tCode  |
+-----------------+--------+
| DOMAIN\Edward   | D11SU1 |
+-----------------+--------+

But how can I manage a user enabled with multiple codes?

e.g.

+-----------------+--------+
| tUser           | tCode  |
+-----------------+--------+
| DOMAIN\Edward   | D11SU1 |
| DOMAIN\Edward   | D11SU2 |
+-----------------+--------+

Is that possible?

My code below

private void recognizeuser()
{
    try
    {
        string cs = ConfigurationManager.ConnectionStrings["con"].ConnectionString;

        using (var connection =
            new MySqlConnection(cs))
        {
            string commandText = " SELECT `tUser`, `tCode` FROM `tUser` " +
                " WHERE `tUser` = @Username; ";

            using (var command = new MySqlCommand(commandText, connection))
            {
                if (!String.IsNullOrEmpty(HttpContext.User.Identity.Name.ToString()))
                {
                    command.Parameters.AddWithValue("@Username", HttpContext.User.Identity.Name.ToString());
                }

                connection.Open();

                string tUser = string.Empty;
                string tCode = string.Empty;

                using (MySqlDataReader reader = command.ExecuteReader())
                {
                    reader.Read();

                    tUser = reader["tUser"].ToString();
                    tCode = reader["tCode"].ToString();

                    System.Web.HttpContext.Current.Session["tUser"] = tUser.ToString();
                    System.Web.HttpContext.Current.Session["tCode"] = tCode.ToString();
                    System.Web.HttpContext.Current.Session.Timeout = 28800;
                }

                if (String.IsNullOrEmpty(userName))
                {
                    ViewBag.Message = String.Format("No user!");
                }

                connection.Close();
            }
        }
    }
    catch (Exception ex)
    {
        TempData["Message"] = "Login failed.Error - " + ex.Message;
    }
}

I using this information (the session) later for populated a drop down list according to the enabling code. I'm going to use a query with WHERE condition e.g.

SELECT * FROM mytable WHERE tCode IN ('D11SU1','D11SU2')