public void userLogin()
        {
            try
            {
                loginCommand = "select User_Name, Password, Role from User_Master where User_Name = '" + login + "'";

                obj = new ConnectDb();
                dr  = obj.getData(loginCommand);

                if (dr.HasRows == true)
                {
                    while (dr.Read())
                    {
                        userID   = dr["User_Name"].ToString();
                        tempPass = dr["Password"].ToString();
                        role     = dr["Role"].ToString();

                        tempPass.Trim();
                        password.Trim();

                        if (password == tempPass)
                        {
                            if (role == "Administrator")
                            {
                                role_Id = 1;
                            }
                            else if (role == "Manager")
                            {
                                role_Id = 2;
                            }
                            else if (role == "Executive")
                            {
                                role_Id = 3;
                            }
                            MessageBox.Show("Welcome " + userID + " to Billing software of " + comboBox1.Text + "", "Login", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
                            this.Hide();
                            Main_Screen md = new Main_Screen(txtLogin.Text, role_Id, company, connectionString);
                            md.ShowDialog();
                        }

                        else
                        {
                            MessageBox.Show("Invalid Password", "Login", MessageBoxButtons.OK, MessageBoxIcon.Error);
                        }
                    }
                }

                else
                {
                    MessageBox.Show("Invalid User name", "Login", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            catch (Exception e)
            {
                MessageBox.Show("The following error occured:\n" + e.Message.ToString(), "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            finally
            {
                dr.Close();
            }
        }