如何制作另一种形式的表单c＃Windows应用程序修改

Question

层次结构： Mainparent（mdi表单） - EMP_loginpage（子表单）

我在下面提供的代码是在EMP_loginpage表单上的提交按钮上编写的。我希望每当用户以 管理员 的身份登录时，另一个表单应该作为Mainparent的子表单而不是EMP_loginpage打开。

CODE ：

private void button1_Click(object sender, EventArgs e)
{

   if (textBox1.Text == "" || textBox2.Text == "")
    {
        MessageBox.Show("User ID or Password Cannot Be Blank...!!", "Stop First Enter UserID and Password", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
        textBox1.Focus();
    }
    else
    {

        if (count == 0)
        {

            try
            {
                con.Open();
                cmd = new SqlCommand("select * from tbllogin where Username='" + textBox1.Text + "' and Password='" + textBox2.Text + "'", con);
                dr = cmd.ExecuteReader();
                if (dr.Read())
                {
                    if (dr["Rights"].ToString()=="1")
                    {

                        uid = dr["Username"].ToString();
                        name = dr["LoginName"].ToString();
                        role = "Administrator";
                        this.Hide();
                        Homeadmin homeadmin = new Homeadmin(); // Homeadmin is the form i want to get opened under mdi(parent) 
                        homeadmin.MdiParent = parent; //  public Mainparent parent=new Mainparent(); where Mainparent is mdi 
                        homeadmin.Show(); // problem is homeadmin doesnt get opened as child form

                        count = 1;
                    }

                    else if (dr["Rights"].ToString() == "2")
                    {
                        uid = dr["Username"].ToString();
                        name = dr["LoginName"].ToString();
                        role = "User";
                        Homestaff homestaff = new Homestaff();
                        this.Hide();
                        this.MdiParent=parent;

                        homestaff.Show();
                        count = 1;
                    }

                    NotifyWindow nw = new NotifyWindow("Employee Management System", "Welcome " + EMP_loginpage.name);



                    nw.SetDimensions(250, 200);
                    nw.Notify();
                }
                else
                {
                    NotifyWindow nw = new NotifyWindow("Employee Management System", "Incorrect Username or password");



                    nw.SetDimensions(250, 200);
                    nw.Notify();
                    MessageBox.Show("User Name Or Password Is Incorrect Please Enter Again", "Wrong Login", MessageBoxButtons.OKCancel, MessageBoxIcon.Error);
                    textBox1.Text = "";
                    textBox2.Text = "";
                    textBox1.Focus();
                }

            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message.ToString(), "Error Message Handled By Try Catch", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            finally
            {
                con.Close();
            }
        }

        else
        {
            MessageBox.Show("Sorry : " + EMP_loginpage.name + " You are already login with the UserID : " + EMP_loginpage.uid + " .So Please first Close Application Or Logout From the Main form", "Stop Error", MessageBoxButtons.OK, MessageBoxIcon.Stop);
        }
    }
}