using (var db = DataContextManager.GetInstance())
            {
                var customer =
                    from c in db.Customers
                    join a in db.Accounts on c.Customer_ID equals a.Customer_ID
                    where c.IsRemoved == false
                    where a.IsRemoved == false
                    where a.Username == username
                    where a.Password == password
                    select new
                    {
                        c.Customer_ID,
                        a.Username,
                        a.Password,
                        a.IsAdmin
                    };

                var result = customer.ToArray();

                if (result == null)
                {
                    lblTest.Text = "Geen geldige gebruiker gevonden";
                }
                else
                {
                    foreach (var i in result)
                    {
                        if (i.IsAdmin == true)
                        {
                            lblTest.Text = "U bent admin!";
                            //set admin user session
                        }
                        else
                        {
                            lblTest.Text = "U bent geen admin!";
                            //set normal user session
                        }
                    }
                }
            }
        }