Restrict certain Users from accessing pages in Windows Form App C#

Samuel Toh

private void btnLogin_Click(object sender, EventArgs e)
{
    if (txtpassword.Text != string.Empty || txtusername.Text != string.Empty)
    {
        
        cmd = new SqlCommand("select * from Login where Username='" + txtusername.Text + "' and Password='" + txtpassword.Text + "'", cn);
        dr = cmd.ExecuteReader();
        if (dr.Read())
        {
            dr.Close();
            this.Hide();
            Home home = new Home();
            home.ShowDialog();
        }
        else
        {
            dr.Close();
            MessageBox.Show("No Account available with this Username and Password ", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }

    }
    else
    {
        MessageBox.Show("Please enter value in all field.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
}

From the above picture, the left side has 6 Buttons. "Login", "Registration", "Home", "About", "Job Application" & "Admin". What I want to achieve is that only normal Users can access all the buttons except "Admin" button, and only Admin uses can access "Admin" button. The codes I have typed below the picture is the code for the login page. During the Login page, no one is allowed to go to any of the pages after clicking the button unless they log in.

So there are two things that I want to achieve:

1. Only normal Users can access all the buttons except "Admin" button, and only Admin uses can access "Admin" button.

2. During the Login page, no one is allowed to go to any of the pages after clicking the button unless they log in.

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Sachin Singh5y ago
Accepted answer
Step 1. if you don't want to create additional IsLoggedIn flag in DB then use static variable.
solution for 2nd part
public static class LoginInfo
{
    public static string UserName;
}

private void btnLogin_Click(object sender, EventArgs e)
        {
            if (txtpassword.Text != string.Empty || txtusername.Text != string.Empty)
            {

                cmd = new SqlCommand("select * from Login where Username='" + txtusername.Text + "' and Password='" + txtpassword.Text + "'", cn);
                dr = cmd.ExecuteReader();
                if (dr.Read())
                {
                    dr.Close();
                    this.Hide();
                    Home home = new Home();
                 LoginInfo.UserName= txtusername.Text; // notice here
                    home.ShowDialog();
                }
                else
                {
                    dr.Close();
                    MessageBox.Show("No Account available with this Username and Password ", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }

            }
            else
            {
                MessageBox.Show("Please enter value in all field.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
step 2. Check for UserName before when they click on other tabs
private void btnAbout_Click(object sender, EventArgs e)
{

if(LoginInfo.UserName==null)
{

MessageBox.Show("Access Denied");
}
solution for second part:-
Add a new file to your project (Add → New Item → Application Configuration File)
The new configuration file will appear in Solution Explorer as App.Config.
Add your settings into this file using the following as a template


   "Admin" value="UserName1"/>





private void btnAdmin_Click(object sender, EventArgs e)
        {

              string AdminName= ConfigurationManager.AppSettings["Admin"];
            if(AdminName==LoginInfo.UserName)
{
// proceed
}else{
MessageBox.Show("Access Denied");
}
        }
+1
Srinivasan Ramamoorthi5y ago
If there are many admins, you can store the Users in database with role column and check if User is normal User or Admin and show and hide the form buttons as needed.

Instead of showing the Admin button and informing you dont have access, you can display only if needed after successful authentication and authorization.

You can create a base class and add method for valudating User is present in database or not and retrieve the role. Add another method to hide/show controls based on roles
Inherit each of these forms using the base class and pass the form reference to toggle the controls visibility.

This will avoid adding code in each form to validate users identity.
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