public bool IsValid(string username, string password)
    {


     string conString = "Server= EJ ; Database=OnlineShopDb ; Integrated Security=SSPI";


        {
            SqlCommand cmd = new SqlCommand("Select * from dbo.UserTb where UserName=@UserName and PassWord=@PassWord");
            SqlConnection con = new SqlConnection(conString);

            cmd.Parameters.AddWithValue("@UserName", SqlDbType.VarChar).Value = username;
            cmd.Parameters.AddWithValue("@PassWord", SqlDbType.VarChar).Value = password;
            con.Open();
            var reader = cmd.ExecuteReader();
            if (reader.HasRows)
            {
                reader.Dispose();
                cmd.Dispose();
                return true;
            }
            else
            {
                reader.Dispose();
                cmd.Dispose();
                return false;
            }
        }
    }