Microsoft Windows Networking: Application Authentication

	Application Authentication

Introduction

Application authentication consists of restricting access to an application. You can first create an application and take care of authentication later, but it is better to design the concept before starting. In this series of articles, we are going to create a complete application, step by step, and in different sections that each deals with one particular issue.

Imagine you want to create an application for a department store. One of the things you can take care of, as far as people who access the program are concerned, is authentication. For our application, you will first create a database.

Practical Learning: Creating a Folder to Hold the Database

Log to the server of your network (normally, you can use any computer of your network)
Create a folder named Fun Department Store
Right-click that folder and click Share
Click the arrow of the combo box in the File Sharing window and select Everyone
Click Add
Click the down-pointing arrow on the right side of Everyone:
- If you are sharing from Microsoft Windows Server 2008, select Contributor
- If you are sharing from Microsoft Windows 7, select Read/Write
Click Share
Click Close

Practical Learning: Creating a Database

In another computer that can access the shared folder and that has Microsoft Access, start Microsoft Access (we will use Microsoft Access 2010)
In the File Name text box, replace the name with FunDS
Click the Browse button
Locate the folder you created and shared from its computer:
Click OK
Click Create
Close the default table without saving it
On the Ribbon, click Create
In the Tables section, click Table Design

Create the following fields

Field Name	Data Type	Field Size	Format	Caption	Other Properties
EmployeeNumber		20		Employee #	Primary Key
FirstName				First Name
LastName		20		Last Name
Title		80
Manager	Yes/No			Manager?
HourlySalary	Number	Double	Fixed	Hourly Salary
Username		20
UserPassword		20		Password

To change the view, right-click the tab of the table and click Datasheet View
When asked to save it, set its name to Employees
Click OK
Create a few records
Close the employees table
On the Ribbon, click Create
In the Tables section, click Table Design

Create the following fields

Field Name	Data Type	Field Size	Format	Caption	Other Properties
ItemNumber		20		Item #	Primary Key
ArrivalDate	Date/Time			Arrival Date
Manufacturer		50
Category		50
SubCategory		50		Sub-Category
ItemName		100		Item Name
ItemSize		50		Item Size
UnitPrice	Number	Double	Fixed	Unit Price
DiscountRate	Number	Double	Fixed	Discount Rate
SaleStatus		40		Sale Status

To switch the view, right-click the table's tab and click Datasheet View
When asked to save it, set its name to StoreItems
Click OK
Create a few records
Close Microsoft Access

Introduction to Implementing Authentication

To implement our authentication, we will create a C# application. Normally, you can use Microsoft Visual C# 2010 Express but we will use Microsoft Visual Studio 2010 Professional. To establish a connection to the Microsoft Access database, we will use the .NET Framework.

As always, you can first create the application and then take care of authentication later.

Practical Learning: Creating a Database

Start Microsoft Visual Studio
To create a new application, on the main menu, click File -> New Project...
If you are using Microsoft Visual Stuio, in the left frame, click Visual C# Projects.
In the middle list, click Empty Project
Set the Name to FunDepartmentStore1
Click OK
On the main menu, click Project -> FunDepartmentStore1 Properties...
In the Output Type combo box, select Windows Application
Close the Properties window
On the main menu, click Project -> Add Reference...
In the Add Reference dialog box, click .NET
In the list view, click System.Data
Press and hold Ctrl
Click System
Click System.Drawing
Click System.Windows.Forms
Click System.Xml
Release Ctrl
Click OK
To create a file for the project, on the main menu, click Project -> Add New Item...
In the middle list, click Code File
Set the Name to StoreInventory
Click Add

In the empty document, type the following:

using System;
using System.Data;
using System.Drawing;
using System.Data.OleDb;
using System.Windows.Forms;
using System.ComponentModel;

public class StoreInventory : Form
{
    private ColumnHeader colIndex;
    private ColumnHeader colItemNumber;
    private ColumnHeader colArrivalDate;
    private ColumnHeader colManufacturer;
    private ColumnHeader colCategory;
    private ColumnHeader colSubCategory;
    private ColumnHeader colItemName;
    private ColumnHeader colItemSize;
    private ColumnHeader colUnitPrice;
    private ColumnHeader colSaleStatus;

    private ListView lvwStoreItems;

    private Button btnClose;

    public StoreInventory()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        colIndex = new ColumnHeader();
        colItemNumber = new ColumnHeader();
        colArrivalDate = new ColumnHeader();
        colManufacturer = new ColumnHeader();
        colCategory = new ColumnHeader();
        colSubCategory = new ColumnHeader();
        colItemName = new ColumnHeader();
        colItemSize = new ColumnHeader();
        colUnitPrice = new ColumnHeader();
        colSaleStatus = new ColumnHeader();

        lvwStoreItems = new ListView();
        btnClose = new Button();

        SuspendLayout();

        colIndex.Text = "Index";
        colIndex.Width = 40;

        colItemNumber.Text = "Item #";
        colItemNumber.TextAlign = HorizontalAlignment.Center;
        colItemNumber.Width = 50;

        colArrivalDate.Text = "Arrival Date";
        colArrivalDate.Width = 70;

        colManufacturer.Text = "Manufacturer";
        colManufacturer.Width = 100;

        colCategory.Text = "Category";
        colSubCategory.Text = "Sub-Category";
        colSubCategory.Width = 80;

        colItemName.Text = "Item Name/Description";
        colItemName.Width = 220;

        colItemSize.Text = "Size";
        colItemSize.TextAlign = HorizontalAlignment.Center;

        colUnitPrice.Text = "Unit Price";
        colUnitPrice.TextAlign = HorizontalAlignment.Right;

        colSaleStatus.Text = "Status";
        colSaleStatus.Width = 70;

        btnClose.Anchor = AnchorStyles.Bottom | AnchorStyles.Right;
        btnClose.Location = new Point(772, 182);
        btnClose.Size = new Size(75, 23);
        btnClose.TabIndex = 33;
        btnClose.Text = "Close";
        btnClose.UseVisualStyleBackColor = true;
        btnClose.Click += new System.EventHandler(btnCloseClicked);

        lvwStoreItems.Anchor = AnchorStyles.Top | AnchorStyles.Bottom |
                               AnchorStyles.Left | AnchorStyles.Right;
        lvwStoreItems.Columns.AddRange(new ColumnHeader[] {
            colIndex, colItemNumber, colArrivalDate, colManufacturer,
            colCategory, colSubCategory, colItemName,
            colItemSize, colUnitPrice, colSaleStatus});
        lvwStoreItems.FullRowSelect = true;
        lvwStoreItems.GridLines = true;
        lvwStoreItems.Location = new Point(12, 12);
        lvwStoreItems.Size = new Size(835, 160);
        lvwStoreItems.TabIndex = 32;
        lvwStoreItems.UseCompatibleStateImageBehavior = false;
        lvwStoreItems.View = System.Windows.Forms.View.Details;

        ClientSize = new Size(859, 213);
        Controls.Add(btnClose);
        Controls.Add(lvwStoreItems);
        ShowInTaskbar = false;
        StartPosition = FormStartPosition.CenterScreen;
        Text = "Fun Department Store - Current Store Inventory";
        Load += new System.EventHandler(StoreInventoryLoaded);

        ResumeLayout(false);
    }

    private void ShowInventory()
    {

    }

    private void StoreInventoryLoaded(object sender, EventArgs e)
    {
        ShowInventory();
    }

    private void btnCloseClicked(object sender, EventArgs e)
    {
        Close();
    }
}

In the Solution Explorer, double-click StoreInventory.cs
To create a new file, on the main menu, click Project -> Add New Item...
In the middle list, click Code File
Set the Name to Switchboard
Click Add

In the empty document, type the following:

using System;
using System.Data;
using System.Drawing;
using System.Data.OleDb;
using System.Windows.Forms;
using System.ComponentModel;

public class Switchboard : Form
{
    private Button btnStoreInventory;
    private Button btnClose;

    public Switchboard()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        btnStoreInventory = new Button();
        btnClose = new Button();

        SuspendLayout();

        btnStoreInventory.Font = new Font("Georgia", 18F, FontStyle.Bold,
                                          GraphicsUnit.Point, 0);
        btnStoreInventory.Location = new Point(11, 12);
        btnStoreInventory.Size = new Size(265, 98);
        btnStoreInventory.TabIndex = 21;
        btnStoreInventory.Text = "View Store Inventory";
        btnStoreInventory.UseVisualStyleBackColor = true;
        btnStoreInventory.Click +=
            new System.EventHandler(btnStoreInventoryClicked);

        btnClose.Font = new Font("Georgia", 18F, FontStyle.Bold,
                                 GraphicsUnit.Point, 0);
        btnClose.Location = new Point(11, 126);
        btnClose.Size = new Size(265, 66);
        btnClose.TabIndex = 22;
        btnClose.Text = "Close Application";
        btnClose.UseVisualStyleBackColor = true;
        btnClose.Click += new System.EventHandler(btnCloseClicked);

        ClientSize = new Size(288, 206);
        Controls.Add(btnStoreInventory);
        Controls.Add(btnClose);
        StartPosition = FormStartPosition.CenterScreen;
        Text = "Fun Department Store - Switchboard";
        Load += new System.EventHandler(SwitchboardLoaded);
        ResumeLayout(false);
    }

    private void btnStoreInventoryClicked(object sender, EventArgs e)
    {
        StoreInventory si = new StoreInventory();
        si.ShowDialog();
    }

    private void btnCloseClicked(object sender, EventArgs e)
    {
        Close();
    }

    private void SwitchboardLoaded(object sender, EventArgs e)
    {

    }
}

public class DepartmentStore
{
    public static int Main()
    {
        Application.Run(new Switchboard());
        return 0;
    }
}

In the Solution Explorer, double-click Switchboard.cs
To execute the application, press F5
Click the View Store Inventory button
Close the Store Inventory form
Close the Switchboard form
Access the StoreInventory.cs file

Implement the ShowInventory() method as follows:

private void ShowInventory()
{
    // If there were some items in the list view, remove them before filling it up
    lvwStoreItems.Items.Clear();

    // To connect to the database, after the following Data Source= expression,
    // type \\, followed by the name of the server (ours is named Expression),
    // followed by \\, followed by the name of the folder where the database 
    // is installed (ours is named Fun Department Store) (of course, you must
    // have shared that folder), followed by \\, and followed by the name of
    // the database, in this case FunDS
    using (OleDbConnection conFunDS =
            new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;" +
                @"Data Source=\\Expression\\Fun Department Store\\FunDS.accdb"))
    {
        // Select all store items
        OleDbCommand cmdFunDS = new OleDbCommand("SELECT * FROM StoreItems;", conFunDS);

        OleDbDataAdapter odaFunDS = new OleDbDataAdapter(cmdFunDS);
        DataSet dsStoreItems = new DataSet("StoreItemsSet");
        odaFunDS.Fill(dsStoreItems);

        conFunDS.Open();

        // Using the total number of records, display each in the list view
        for (int i = 0; i < dsStoreItems.Tables[0].Rows.Count; i++)
        {
            DataRow rcdStoreItem = dsStoreItems.Tables[0].Rows[i];

            ListViewItem lviStoreItem = new ListViewItem((i + 1).ToString());
            lviStoreItem.SubItems.Add(rcdStoreItem["ItemNumber"].ToString());
            lviStoreItem.SubItems.Add(
                        DateTime.Parse(rcdStoreItem["ArrivalDate"].ToString()).ToShortDateString());
            lviStoreItem.SubItems.Add(rcdStoreItem["Manufacturer"].ToString());
            lviStoreItem.SubItems.Add(rcdStoreItem["Category"].ToString());
            lviStoreItem.SubItems.Add(rcdStoreItem["SubCategory"].ToString());
            lviStoreItem.SubItems.Add(rcdStoreItem["ItemName"].ToString());
            lviStoreItem.SubItems.Add(rcdStoreItem["ItemSize"].ToString());
            lviStoreItem.SubItems.Add(
                    double.Parse(rcdStoreItem["UnitPrice"].ToString()).ToString("F"));
            lviStoreItem.SubItems.Add(rcdStoreItem["SaleStatus"].ToString());
            lvwStoreItems.Items.Add(lviStoreItem);
        }
    }
}

private void StoreInventory_Load(object sender, EventArgs e)
{
    ShowInventory();
}

To execute, press F5
Click the Store Inventory button
Close the Store Inventory form
Close the Switchboard form

Implementing Authentication

There is always more than one way to solve a problem in logic and in math. When it comes to an application also, you have many options:

You can create the first form of your application as the log in dialog box. In this case, if the employee successfully logs, then the actual application would display
You can add the code to call a log in dialog box to the first form. If the employee successfully logs in, then the rest of the application would show

In all cases, you must decide when and how the employee would log in and what to do in case of successful or unsuccessful log in.

Practical Learning: Implementing Authentication

To create a file, on the main menu, click Project -> Add New Item...
In the middle list, click Code File
Set the Name to Authenticator
Click Add

In the empty document, type the following:

using System;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using System.ComponentModel;

public class Authenticator : Form
{
    private Label lblUsername;
    public TextBox txtUsername;
    private Label lblPassword;
    public TextBox txtPassword;
    private Button btnOK;
    private Button btnCancel;

    public Authenticator()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        lblUsername = new Label();
        txtUsername = new TextBox();
        txtPassword = new TextBox();
        lblPassword = new Label();
        btnOK = new Button();
        btnCancel = new Button();

        this.SuspendLayout();

        lblUsername.AutoSize = true;
        lblUsername.Location = new Point(12, 19);
        lblUsername.Size = new Size(58, 13);
        lblUsername.TabIndex = 0;
        lblUsername.Text = "Username:";

        txtUsername.Location = new Point(87, 16);
        txtUsername.Size = new Size(100, 20);
        txtUsername.TabIndex = 1;

        lblPassword.AutoSize = true;
        lblPassword.Location = new Point(12, 45);
        lblPassword.Size = new Size(56, 13);
        lblPassword.TabIndex = 2;
        lblPassword.Text = "Password:";

        txtPassword.Location = new Point(87, 42);
        txtPassword.PasswordChar = '*';
        txtPassword.Size = new Size(100, 20);
        txtPassword.TabIndex = 3;

        btnOK.DialogResult = System.Windows.Forms.DialogResult.OK;
        btnOK.Location = new Point(31, 78);
        btnOK.Size = new Size(75, 23);
        btnOK.TabIndex = 4;
        btnOK.Text = "OK";
        btnOK.UseVisualStyleBackColor = true;

        btnCancel.DialogResult = System.Windows.Forms.DialogResult.Cancel;
        btnCancel.Location = new Point(112, 78);
        btnCancel.Size = new Size(75, 23);
        btnCancel.TabIndex = 5;
        btnCancel.Text = "Cancel";
        btnCancel.UseVisualStyleBackColor = true;

        Controls.Add(lblUsername);
        Controls.Add(txtUsername);
        Controls.Add(lblPassword);
        Controls.Add(txtPassword);
        Controls.Add(btnOK);
        Controls.Add(btnCancel);

        AcceptButton = btnOK;
        CancelButton = btnCancel;
        ClientSize = new Size(206, 115);
        FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
        MaximizeBox = false;
        MinimizeBox = false;
        ShowInTaskbar = false;
        StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
        Text = "Fun Department Store - Log In";
        ResumeLayout(false);
    }
}

In the Solution Explorer, double-click Authenticator.cs
Access the Switchboard.cs file

Create a method named LogInToTheApplication and change the SwitchboardLoaded event as follows:

private void LogInToTheApplication()
{
    bool usernamePasswordMatch = false;
    Authenticator dlgLogIn = new Authenticator();
    string strPasswordFromDialogBox = "", strPasswordFromDatabase = "";
    string strUsernameFromDialogBox = "", strUsernameFromDatabase = "";

    // Display the Autheticator dialog box.
    // If the user clicks Cancel, simply close the application
    if (dlgLogIn.ShowDialog() == System.Windows.Forms.DialogResult.Cancel)
        Close();
    else // If the user clicks OK
    {
        // If the employee doesn't enter a username, display a message box...
        if (dlgLogIn.txtUsername.Text == "")
        {
            MessageBox.Show("You must enter a user name.",
                            "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
            // ... and close the application
            Close();
        }

        // If the employee doesn't enter a password, display a message box...
        if (dlgLogIn.txtPassword.Text == "")
        {
            MessageBox.Show("You must type a password.",
                            "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
            // ... and close the application
            Close();
        }

        // Get the user name of the dialog box
        strUsernameFromDialogBox = dlgLogIn.txtUsername.Text;
        // Get the password of the dialog box
        strPasswordFromDialogBox = dlgLogIn.txtPassword.Text;

        // To connect to the database, after the following Data Source= expression,
        // type \\, followed by the name of the server (ours is named Expression),
        // followed by \\, followed by the name of the folder where the database 
        // is installed (ours is named Fun Department Store) (of course, you must
        // have shared that folder), followed by \\, and followed by the name of
        // the database, in this case FunDS
        using (OleDbConnection conFunDS =
                new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;" +
                    @"Data Source=\\Expression\\Fun Department Store\\FunDS.accdb"))
        {
            // Get the records of all employees
            OleDbCommand cmdFunDS = new OleDbCommand("SELECT * FROM Employees;", conFunDS);

            // Create a data adapater to retrieve the employees
            OleDbDataAdapter odaEmployees = new OleDbDataAdapter(cmdFunDS);
            // Create a data set of employees
            DataSet dsEmployees = new DataSet("EmployeesSet");
            // Fill the data set with the Employees records
            odaEmployees.Fill(dsEmployees);

            // Open the connection
            conFunDS.Open();

            // Navigate to each record
            for (int i = 0; i < dsEmployees.Tables[0].Rows.Count; i++)
            {
                // Get a reference to the current record
                DataRow rcdStoreItem = dsEmployees.Tables[0].Rows[i];

                // When you are on a record, get the username of the employee
                strUsernameFromDatabase = rcdStoreItem["Username"].ToString();
                // and the password
                strPasswordFromDatabase = rcdStoreItem["UserPassword"].ToString();

                // Compare the current username to the username of the dialog box
                // and the current password to the password of the dialog box.
                // If they match, ...
                if (strUsernameFromDatabase.Equals(strUsernameFromDialogBox) &&
                    strPasswordFromDatabase.Equals(strPasswordFromDialogBox))
                {
                    usernamePasswordMatch = true;
                    // ... display the switchboard
                    break;
                }

                // If there is no match, continue to the next record, 
                // up to the end of the table
            }

            // If there was a match for username/password, display the Switchboard

            // If there was no match for username/password, 
            // Let the employee know ...
            if (usernamePasswordMatch == false)
            {
                MessageBox.Show("The username and password combination did " +
                                "not match any of the employees",
                                "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
                // ... and close the application
                Close();
            }
        }
    }
}

private void SwitchboardLoaded(object sender, EventArgs e)
{
    LogInToTheApplication();
}

To test the application, press F5
When the dialog box comes up, click Cancel
Execute the application again
When the dialog box displays, type the user name as Pasquale and press Enter
Read the message box and click OK
Execute the application again
When the dialog box displays, type the user name as opasquale and press Tab
Type the password as L'Italiano and press Enter
Read the message box and press Enter
Execute the application again
Type the username as mtownsend and press Tab
Type the password as Password4 and pass Enter
Read the message box and click OK
Execute the application again
In the username of the dialog box, type mtownsend and press Tab
Type the password as Password5
Click OK
Click the View Store Inventory button
Close the forms
To create a new file, on the main menu, click Project -> Add New Item...
In the middle list, click Code File
Set the Name to CreateStoreItem
Click Add

In the empty document, type the following:

using System;
using System.Data;
using System.Drawing;
using System.Data.OleDb;
using System.Windows.Forms;
using System.ComponentModel;

public class CreateStoreItem : Form
{
    private Label lblItemNumber;
    private TextBox txtItemNumber;
    private Label lblArrivalDate;
    private MaskedTextBox txtArrivalDate;
    private Label lblManufacturer;
    private TextBox txtManufacturer;
    private Label lblCategory;
    private ComboBox cbxCategories;
    private Label lblSubCategory;
    private ComboBox cbxSubCategories;
    private Label lblItemName;
    private TextBox txtItemName;
    private Label lblItemSize;
    private TextBox txtItemSize;
    private Label lblUnitPrice;
    private TextBox txtUnitPrice;
    private Label lblDiscountRate;
    private TextBox txtDiscountRate;
    private Label lblPercent;
    private Label lblSaleStatus;
    private ComboBox cbxSaleStatus;

    private Button btnReset;
    private Button btnCreate;
    private Button btnClose;

    public CreateStoreItem()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        lblItemNumber = new Label();
        txtItemNumber = new TextBox();
        lblArrivalDate = new Label();
        txtArrivalDate = new MaskedTextBox();
        lblManufacturer = new Label();
        txtManufacturer = new TextBox();
        lblCategory = new Label();
        cbxCategories = new ComboBox();
        lblSubCategory = new Label();
        cbxSubCategories = new ComboBox();
        lblItemName = new Label();
        txtItemName = new TextBox();
        lblItemSize = new Label();
        txtItemSize = new TextBox();
        lblUnitPrice = new Label();
        txtUnitPrice = new TextBox();
        lblDiscountRate = new Label();
        txtDiscountRate = new TextBox();
        lblPercent = new Label();
        lblSaleStatus = new Label();
        cbxSaleStatus = new ComboBox();

        btnReset = new Button();
        btnCreate = new Button();
        btnClose = new Button();

        SuspendLayout();

        lblItemNumber.AutoSize = true;
        lblItemNumber.Location = new Point(11, 14);
        lblItemNumber.Size = new Size(40, 13);
        lblItemNumber.TabIndex = 0;
        lblItemNumber.Text = "Item #:";

        txtItemNumber.Location = new Point(95, 11);
        txtItemNumber.Size = new Size(96, 20);
        txtItemNumber.TabIndex = 1;

        lblArrivalDate.AutoSize = true;
        lblArrivalDate.Location = new Point(223, 14);
        lblArrivalDate.Size = new Size(65, 13);
        lblArrivalDate.TabIndex = 2;
        lblArrivalDate.Text = "Arrival Date:";

        txtArrivalDate.Location = new Point(303, 11);
        txtArrivalDate.Mask = "00/00/0000";
        txtArrivalDate.Size = new Size(121, 20);
        txtArrivalDate.TabIndex = 3;
        txtArrivalDate.ValidatingType = typeof(System.DateTime);
   
        lblManufacturer.AutoSize = true;
        lblManufacturer.Location = new Point(11, 43);
        lblManufacturer.Size = new Size(73, 13);
        lblManufacturer.TabIndex = 4;
        lblManufacturer.Text = "Manufacturer:";

        txtManufacturer.Location = new Point(95, 40);
        txtManufacturer.Size = new Size(330, 20);
        txtManufacturer.TabIndex = 5;

        lblCategory.AutoSize = true;
        lblCategory.Location = new Point(11, 72);
        lblCategory.Size = new Size(52, 13);
        lblCategory.TabIndex = 6;
        lblCategory.Text = "Category:";

        cbxCategories.FormattingEnabled = true;
        cbxCategories.Items.AddRange(new object[] {
            "Men", "Girls", "Boys",
            "Babies", "Women", "Other"});
        cbxCategories.Location = new Point(95, 70);
        cbxCategories.Size = new Size(116, 21);
        cbxCategories.TabIndex = 7;

        lblSubCategory.AutoSize = true;
        lblSubCategory.Location = new Point(223, 73);
        lblSubCategory.Size = new Size(74, 13);
        lblSubCategory.TabIndex = 8;
        lblSubCategory.Text = "Sub-Category:";

        cbxSubCategories.FormattingEnabled = true;
        cbxSubCategories.Items.AddRange(new object[] {
            "Skirts", "Pants", "Shirts", "Shoes",
            "Blouse", "Beauty", "Dresses", "Clothing",
            "Sweater", "Watches", "Handbags", "Miscellaneous"});
        cbxSubCategories.Location = new Point(303, 70);
        cbxSubCategories.Size = new Size(121, 21);
        cbxSubCategories.TabIndex = 9;

        lblItemName.AutoSize = true;
        lblItemName.Location = new Point(11, 104);
        lblItemName.Size = new Size(61, 13);
        lblItemName.TabIndex = 10;
        lblItemName.Text = "Item Name:";
 
        txtItemName.Location = new Point(95, 100);
        txtItemName.Size = new Size(329, 20);
        txtItemName.TabIndex = 11;

        lblItemSize.AutoSize = true;
        lblItemSize.Location = new Point(12, 132);
        lblItemSize.Size = new Size(30, 13);
        lblItemSize.TabIndex = 12;
        lblItemSize.Text = "Size:";
 
        txtItemSize.Location = new Point(95, 129);
        txtItemSize.Size = new Size(96, 20);
        txtItemSize.TabIndex = 13;

        lblUnitPrice.AutoSize = true;
        lblUnitPrice.Location = new Point(224, 135);
        lblUnitPrice.Size = new Size(56, 13);
        lblUnitPrice.TabIndex = 14;
        lblUnitPrice.Text = "Unit Price:";
 
        txtUnitPrice.Location = new Point(304, 132);
        txtUnitPrice.Size = new Size(121, 20);
        txtUnitPrice.TabIndex = 15;
        txtUnitPrice.Text = "0.00";
        txtUnitPrice.TextAlign = HorizontalAlignment.Right;

        lblDiscountRate.AutoSize = true;
        lblDiscountRate.Location = new Point(11, 161);
        lblDiscountRate.Size = new Size(78, 13);
        lblDiscountRate.TabIndex = 16;
        lblDiscountRate.Text = "Discount Rate:";

        txtDiscountRate.Location = new Point(95, 158);
        txtDiscountRate.Size = new Size(96, 20);
        txtDiscountRate.TabIndex = 17;
        txtDiscountRate.Text = "0.00";
        txtDiscountRate.TextAlign = HorizontalAlignment.Right;

        lblPercent.AutoSize = true;
        lblPercent.Font = new Font("Microsoft Sans Serif", 9.75F,
            FontStyle.Bold, GraphicsUnit.Point, 0);
        lblPercent.Location = new Point(191, 161);
        lblPercent.Size = new Size(21, 16);
        lblPercent.TabIndex = 18;
        lblPercent.Text = "%";

        lblSaleStatus.AutoSize = true;
        lblSaleStatus.Location = new Point(224, 164);
        lblSaleStatus.Name = "lblSaleStatus";
        lblSaleStatus.Size = new Size(64, 13);
        lblSaleStatus.TabIndex = 19;
        lblSaleStatus.Text = "Sale Status:";
 
        cbxSaleStatus.FormattingEnabled = true;
        cbxSaleStatus.Items.AddRange(new object[] {
            "Sold", "In Stock", "On Display",
            "Processing", "Other"});
        cbxSaleStatus.Location = new Point(304, 161);
        cbxSaleStatus.Size = new Size(121, 21);
        cbxSaleStatus.TabIndex = 20;
 
        btnReset.Location = new Point(125, 193);
        btnReset.Size = new Size(95, 23);
        btnReset.TabIndex = 23;
        btnReset.Text = "Reset";
        btnReset.UseVisualStyleBackColor = true;
        btnReset.Click += new System.EventHandler(btnResetClicked);

        btnCreate.Location = new Point(226, 193);
        btnCreate.Size = new Size(108, 23);
        btnCreate.TabIndex = 21;
        btnCreate.Text = "Create";
        btnCreate.UseVisualStyleBackColor = true;
        btnCreate.Click += new System.EventHandler(btnCreateClicked);

        btnClose.Location = new Point(340, 193);
        btnClose.Size = new Size(83, 23);
        btnClose.TabIndex = 22;
        btnClose.Text = "Close";
        btnClose.UseVisualStyleBackColor = true;
        btnClose.Click += new System.EventHandler(btnClose_Click);
 
        Controls.Add(lblItemNumber);
        Controls.Add(txtItemNumber);
        Controls.Add(lblArrivalDate);
        Controls.Add(txtArrivalDate);
        Controls.Add(lblManufacturer);
        Controls.Add(txtManufacturer);
        Controls.Add(lblCategory);
        Controls.Add(cbxCategories);
        Controls.Add(lblSubCategory);
        Controls.Add(cbxSubCategories);
        Controls.Add(lblItemName);
        Controls.Add(txtItemName);
        Controls.Add(lblItemSize);
        Controls.Add(txtItemSize);
        Controls.Add(lblUnitPrice);
        Controls.Add(txtUnitPrice);
        Controls.Add(lblDiscountRate);
        Controls.Add(txtDiscountRate);
        Controls.Add(lblPercent);
        Controls.Add(lblSaleStatus);
        Controls.Add(cbxSaleStatus);

        Controls.Add(btnCreate);
        Controls.Add(btnReset);
        Controls.Add(btnClose);

        ClientSize = new Size(437, 230);
        FormBorderStyle = FormBorderStyle.FixedDialog;
        MaximizeBox = false;
        MinimizeBox = false;
        ShowInTaskbar = false;
        StartPosition = FormStartPosition.CenterScreen;
        Text = "Fun Department Store - Create New Store Item";
        Load += new System.EventHandler(CreateStoreItemLoaded);
        ResumeLayout(false);
        PerformLayout();

    }

    private void btnResetClicked(object sender, EventArgs e)
    {
        txtItemNumber.Text = "";
        txtArrivalDate.Text = DateTime.Today.ToShortDateString();
        txtManufacturer.Text = "";
        cbxCategories.Text = "";
        cbxSubCategories.Text = "";
        txtItemName.Text = "";
        txtItemSize.Text = "";
        txtUnitPrice.Text = "0.00";
        txtDiscountRate.Text = "0.00";
        cbxSaleStatus.Text = "In Stock";
    }

    private void CreateStoreItemLoaded(object sender, EventArgs e)
    {
        // When the form opens, reset it
        btnResetClicked(sender, e);
    }

    private void btnCreateClicked(object sender, EventArgs e)
    {
        double unitPrice = 0.00;
        double discountRate = 0.00;

        // Make sure the user entered an item number.
        // If not, don't do anything
        if (txtItemNumber.Text.Length == 0)
        {
            MessageBox.Show("You must provide a (unique) item number.",
                            "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
            return;
        }
        // On a related issue, for the simplicity of this exercise,
        // We are not writing code to check whether the user provided
        // a duplicate item number. If the user does, the application
        // itself would throw an exception. In another article, we may have
        // to take care of that problem. For now, we will ignore it

        // Make sure the user entered a name for the new item.
        // If not, don't do anything
        if (txtItemName.Text.Length == 0)
        {
            MessageBox.Show("You must provide a name for the item.",
                            "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
            return;
        }

        // Make sure the user provided a price for the item
        if (txtUnitPrice.Text.Length == 0)
        {
            MessageBox.Show("You must provide a price for the item.",
                            "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
            return;
        }

        // Check if the user provided a valid price...
        try
        {
            unitPrice = double.Parse(txtUnitPrice.Text);
        }
        catch (FormatException)
        {
            // ... if not, use 0.00
        }

        // Check if the user provided a valid discount rate...
        try
        {
            discountRate = double.Parse(txtDiscountRate.Text);
        }
        catch (FormatException)
        {
            // ... if not, use 0.00
        }

        // Connect to the database
        // To connect to the database, after the following Data Source= expression,
        // type \\, followed by the name of the server (ours is named Expression),
        // followed by \\, followed by the name of the folder where the database 
        // is installed (ours is named Fun Department Store) (of course, you must
        // have shared that folder), followed by \\, and followed by the name of
        // the database, in this case FunDS
        using (OleDbConnection conFunDS =
                        new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;" +
                            @"Data Source=\\Expression\\Fun Department Store\\FunDS.accdb"))
        {
            string strSQLInsert = "INSERT INTO StoreItems(ItemNumber, ArrivalDate, " +
                                       "Manufacturer, Category, SubCategory, ItemName, " +
                                       "ItemSize, UnitPrice, DiscountRate, SaleStatus) " +
                                       "VALUES(" + txtItemNumber.Text + ", '" +
                                                   txtArrivalDate.Text + "', '" +
                                                   txtManufacturer.Text + "', '" +
                                                   cbxCategories.Text + "', '" +
                                                   cbxSubCategories.Text + "', '" +
                                                   txtItemName.Text + "', '" +
                                                   txtItemSize.Text + "', " +
                                                   unitPrice + ", " +
                                                   discountRate + ", '" +
                                                   cbxSaleStatus.Text + "');";

            // Generate a command to create a record
            OleDbCommand cmdStoreItems = new OleDbCommand(strSQLInsert, conFunDS);

            conFunDS.Open();
            cmdStoreItems.ExecuteNonQuery();

            // Once the item has been created, let the user know
            MessageBox.Show("The item has been created",
                            "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);

            btnResetClicked(sender, e);
        }
    }

    private void btnClose_Click(object sender, EventArgs e)
    {
        Close();
    }
}

In the Solution Explorer, double-click Authenticator.cs
To create a new file, on the main menu, click Project -> Add New Item
In the middle list, make sure Code File is selected.
Change the name to Employees
Click Add

In the empty document, type the following:

using System;
using System.IO;
using System.Data;
using System.Drawing;
using System.Data.OleDb;
using System.Windows.Forms;
using System.ComponentModel;

public class Employees : Form
{
    private ColumnHeader colEmployeeNumber;
    private ColumnHeader colFirstName;
    private ColumnHeader colLastName;
    private ColumnHeader colTitle;
    private ColumnHeader colManager;
    private ColumnHeader colHourlySalary;
    private ColumnHeader colUsername;
    private ColumnHeader colPassword;
    private ListView lvwEmployees;

    public  GroupBox grpNewEmployee;
    private Label lblEmployeeNumber;
    private MaskedTextBox txtEmployeeNumber;
    private Label lblFirstName;
    private TextBox txtFirstName;
    private Label lblLastName;
    private TextBox txtLastName;
    private Label lblTitle;
    private TextBox txtTitle;
    private Button btnReset;
    private CheckBox chkManager;
    private Label lblHourlySalary;
    private TextBox txtHourlySalary;
    private Button btnSubmit;
    private Label lblUsername;
    private TextBox txtUsername;
    private Label lblPassword;
    private TextBox txtPassword;
    private Button btnClose;

    public Employees()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        colEmployeeNumber = new ColumnHeader();
        colFirstName = new ColumnHeader();
        colLastName = new ColumnHeader();
        colTitle = new ColumnHeader();
        colManager = new ColumnHeader();
        colHourlySalary = new ColumnHeader();
        colUsername = new ColumnHeader();
        colPassword = new ColumnHeader();
        lvwEmployees = new ListView();

        grpNewEmployee = new GroupBox();
        lblEmployeeNumber = new Label();
        txtEmployeeNumber = new MaskedTextBox();
        lblFirstName = new Label();
        txtFirstName = new TextBox();
        lblLastName = new Label();
        txtLastName = new TextBox();
        lblTitle = new Label();
        txtTitle = new TextBox();
        btnReset = new Button();
        chkManager = new CheckBox();
        lblHourlySalary = new Label();
        txtHourlySalary = new TextBox();
        btnSubmit = new Button();
        lblUsername = new Label();
        txtUsername = new TextBox();
        lblPassword = new Label();
        txtPassword = new TextBox();
        btnClose = new Button();

        grpNewEmployee.SuspendLayout();
        SuspendLayout();

        colEmployeeNumber.Text = "Employee #";
        colEmployeeNumber.Width = 70;

        colFirstName.Text = "First Name";
        colFirstName.Width = 80;

        colLastName.Text = "Last Name";
        colLastName.Width = 80;

        colTitle.Text = "Title";
        colTitle.Width = 120;

        colManager.Text = "Manager";

        colHourlySalary.Text = "Salary";
        colHourlySalary.TextAlign = System.Windows.Forms.HorizontalAlignment.Right;
        colHourlySalary.Width = 50;

        colUsername.Text = "Username";

        colPassword.Text = "Password";

        lvwEmployees.Columns.AddRange(new ColumnHeader[] {
            colEmployeeNumber, colFirstName, colLastName, colTitle,
            colManager, colHourlySalary, colUsername, colPassword});
        lvwEmployees.FullRowSelect = true;
        lvwEmployees.GridLines = true;
        lvwEmployees.Location = new Point(12, 12);
        lvwEmployees.Size = new Size(606, 191);
        lvwEmployees.TabIndex = 0;
        lvwEmployees.UseCompatibleStateImageBehavior = false;
        lvwEmployees.View = System.Windows.Forms.View.Details;

        grpNewEmployee.Controls.Add(lblEmployeeNumber);
        grpNewEmployee.Controls.Add(txtEmployeeNumber);
        grpNewEmployee.Controls.Add(lblFirstName);
        grpNewEmployee.Controls.Add(txtFirstName);
        grpNewEmployee.Controls.Add(lblLastName);
        grpNewEmployee.Controls.Add(txtLastName);
        grpNewEmployee.Controls.Add(lblTitle);
        grpNewEmployee.Controls.Add(txtTitle);
        grpNewEmployee.Controls.Add(btnReset);
        grpNewEmployee.Controls.Add(chkManager);
        grpNewEmployee.Controls.Add(lblHourlySalary);
        grpNewEmployee.Controls.Add(txtHourlySalary);
        grpNewEmployee.Controls.Add(btnSubmit);
        grpNewEmployee.Controls.Add(lblUsername);
        grpNewEmployee.Controls.Add(txtUsername);
        grpNewEmployee.Controls.Add(lblPassword);
        grpNewEmployee.Controls.Add(txtPassword);
        grpNewEmployee.Location = new Point(12, 209);
        grpNewEmployee.Size = new Size(605, 165);
        grpNewEmployee.TabIndex = 1;
        grpNewEmployee.TabStop = false;
        grpNewEmployee.Text = "New Employee";

        lblEmployeeNumber.AutoSize = true;
        lblEmployeeNumber.Location = new Point(42, 29);
        lblEmployeeNumber.Size = new Size(66, 13);
        lblEmployeeNumber.TabIndex = 0;
        lblEmployeeNumber.Text = "Employee #:";

        txtEmployeeNumber.Location = new Point(124, 26);
        txtEmployeeNumber.Mask = "00-000";
        txtEmployeeNumber.Size = new Size(52, 20);
        txtEmployeeNumber.TabIndex = 1;

        lblFirstName.AutoSize = true;
        lblFirstName.Location = new Point(42, 55);
        lblFirstName.Size = new Size(60, 13);
        lblFirstName.TabIndex = 2;
        lblFirstName.Text = "First Name:";

        txtFirstName.Location = new Point(124, 52);
        txtFirstName.Size = new Size(100, 20);
        txtFirstName.TabIndex = 3;

        lblLastName.AutoSize = true;
        lblLastName.Location = new Point(245, 55);
        lblLastName.Size = new Size(61, 13);
        lblLastName.TabIndex = 4;
        lblLastName.Text = "Last Name:";

        txtLastName.Location = new Point(327, 52);
        txtLastName.Name = "txtLastName";
        txtLastName.Size = new Size(100, 20);
        txtLastName.TabIndex = 5;

        lblTitle.AutoSize = true;
        lblTitle.Location = new Point(42, 81);
        lblTitle.Size = new Size(30, 13);
        lblTitle.TabIndex = 6;
        lblTitle.Text = "Title:";

        txtTitle.Location = new Point(124, 78);
        txtTitle.Name = "txtTitle";
        txtTitle.Size = new Size(303, 20);
        txtTitle.TabIndex = 7;

        btnReset.Location = new Point(447, 104);
        btnReset.Size = new Size(97, 23);
        btnReset.TabIndex = 15;
        btnReset.Text = "Reset";
        btnReset.UseVisualStyleBackColor = true;
        btnReset.Click += new System.EventHandler(btnResetClicked);

        chkManager.AutoSize = true;
        chkManager.CheckAlign = ContentAlignment.MiddleRight;
        chkManager.Location = new Point(45, 107);
        chkManager.Size = new Size(91, 17);
        chkManager.TabIndex = 8;
        chkManager.Text = "Is a Manager:";
        chkManager.UseVisualStyleBackColor = true;

        lblHourlySalary.AutoSize = true;
        lblHourlySalary.Location = new Point(245, 107);
        lblHourlySalary.Size = new Size(72, 13);
        lblHourlySalary.TabIndex = 9;
        lblHourlySalary.Text = "Hourly Salary:";

        txtHourlySalary.Location = new Point(327, 104);
        txtHourlySalary.Size = new Size(100, 20);
        txtHourlySalary.TabIndex = 10;
        txtHourlySalary.Text = "0.00";
        txtHourlySalary.TextAlign = HorizontalAlignment.Right;

        btnSubmit.Location = new Point(447, 132);
        btnSubmit.Size = new Size(97, 23);
        btnSubmit.TabIndex = 16;
        btnSubmit.Text = "Submit";
        btnSubmit.UseVisualStyleBackColor = true;
        btnSubmit.Click += new System.EventHandler(btnSubmitClicked);

        lblUsername.AutoSize = true;
        lblUsername.Location = new Point(42, 133);
        lblUsername.Size = new Size(58, 13);
        lblUsername.TabIndex = 11;
        lblUsername.Text = "Username:";

        txtUsername.Location = new Point(124, 130);
        txtUsername.Size = new Size(100, 20);
        txtUsername.TabIndex = 12;

        lblPassword.AutoSize = true;
        lblPassword.Location = new Point(245, 132);
        lblPassword.Size = new Size(56, 13);
        lblPassword.TabIndex = 13;
        lblPassword.Text = "Password:";

        txtPassword.Location = new Point(327, 130);
        txtPassword.PasswordChar = '*';
        txtPassword.Size = new Size(100, 20);
        txtPassword.TabIndex = 14;

        btnClose.Location = new Point(459, 384);
        btnClose.Size = new Size(97, 23);
        btnClose.TabIndex = 17;
        btnClose.Text = "Close";
        btnClose.UseVisualStyleBackColor = true;
        btnClose.Click += new System.EventHandler(btnCloseClicked);

        ClientSize = new Size(629, 414);
        Controls.Add(grpNewEmployee);
        Controls.Add(lvwEmployees);
        Controls.Add(btnClose);
        FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
        MaximizeBox = false;
        MinimizeBox = false;
        ShowInTaskbar = false;
        StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
        Text = "Fun Department Store - Employees";
        Load += new System.EventHandler(Employees_Load);
        grpNewEmployee.ResumeLayout(false);
        grpNewEmployee.PerformLayout();
        ResumeLayout(false);

    }

    private void ShowEmployees()
    {
        lvwEmployees.Items.Clear();

        // To connect to the database, after the following Data Source= expression,
        // type \\, followed by the name of the server (ours is named Expression),
        // followed by \\, followed by the name of the folder where the database 
        // is installed (ours is named Fun Department Store) (of course, you must
        // have shared that folder), followed by \\, and followed by the name of
        // the database, in this case FunDS
        using (OleDbConnection conFunDS =
                new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;" +
                    @"Data Source=\\Expression\\Fun Department Store\\FunDS.accdb"))
        {
            // Select all store items
            OleDbCommand cmdFunDS = new OleDbCommand("SELECT * FROM Employees;", conFunDS);

            OleDbDataAdapter odaFunDS = new OleDbDataAdapter(cmdFunDS);
            DataSet dsEmployees = new DataSet("EmployeesSet");
            odaFunDS.Fill(dsEmployees);

            conFunDS.Open();

            // Using the total number of records, display each in the list view
            for (int i = 0; i < dsEmployees.Tables[0].Rows.Count; i++)
            {
                DataRow rcdEmployee = dsEmployees.Tables[0].Rows[i];

                ListViewItem lviEmployee = new ListViewItem((i + 1).ToString());
                lviEmployee.SubItems.Add(rcdEmployee["employeeNumber"].ToString());
                lviEmployee.SubItems.Add(rcdEmployee["FirstName"].ToString());
                lviEmployee.SubItems.Add(rcdEmployee["LastName"].ToString());
                lviEmployee.SubItems.Add(rcdEmployee["Title"].ToString());
                lviEmployee.SubItems.Add(rcdEmployee["Manager"].ToString());
                lviEmployee.SubItems.Add(rcdEmployee["HourlySalary"].ToString());
                lviEmployee.SubItems.Add(rcdEmployee["Username"].ToString());
                lviEmployee.SubItems.Add(rcdEmployee["UserPassword"].ToString());
                lvwEmployees.Items.Add(lviEmployee);
            }
        }
    }

    private void Employees_Load(object sender, EventArgs e)
    {
        ShowEmployees();
        btnResetClicked(sender, e);
    }

    private void btnResetClicked(object sender, EventArgs e)
    {
        Random rndNumber = new Random();

        txtEmployeeNumber.Text = rndNumber.Next(10000, 99999).ToString();
        txtFirstName.Text = "";
        txtLastName.Text = "";
        txtTitle.Text = "";
        chkManager.Checked = false;
        txtHourlySalary.Text = "0.00";
        txtUsername.Text = "";
        txtPassword.Text = "";
    }

    private void btnSubmitClicked(object sender, EventArgs e)
    {
        double hourlySalary = 0.00;

        try
        {
            hourlySalary = double.Parse(txtHourlySalary.Text);
        }
        catch (FormatException)
        {
        }

        // Connect to the database
        // To connect to the database, after the following Data Source= expression,
        // type \\, followed by the name of the server (ours is named Expression),
        // followed by \\, followed by the name of the folder where the database 
        // is installed (ours is named Fun Department Store) (of course, you must
        // have shared that folder), followed by \\, and followed by the name of
        // the database, in this case FunDS
        using (OleDbConnection conFunDS =
                        new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;" +
                            @"Data Source=\\Expression\\Fun Department Store\\FunDS.accdb"))
        {
            string strSQLInsert = "INSERT INTO Employees(EmployeeNumber, FirstName, " +
                                       "LastName, Title, Manager, HourlySalary, " +
                                       "Username, UserPassword) VALUES('" +
                                       txtEmployeeNumber.Text + "', '" +
                                       txtFirstName.Text + "', '" +
                                       txtLastName.Text + "', '" +
                                       txtTitle.Text + "', " +
                                       chkManager.Checked + ", " +
                                       hourlySalary + ", '" +
                                       txtUsername.Text + "', '" +
                                       txtPassword.Text + "');";

            // Generate a command to create a record
            OleDbCommand cmdEmployees = new OleDbCommand(strSQLInsert, conFunDS);

            conFunDS.Open();
            cmdEmployees.ExecuteNonQuery();

            MessageBox.Show("The employee has been created.",
                            "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);

            btnResetClicked(sender, e);
        }
    }

    private void btnCloseClicked(object sender, EventArgs e)
    {
        Close();
    }
}

Save all

Contextual Access

We refer to contextual the ability to grant access or some operations to one or more objects of an application to one or more people. This may sound complicated but it really is not. Or the real difficulty lies, not in programming, but in logic and organization (design). One way to solve the problem would consist of making a list of objects in your application, another list of people in your organization, then specify who will have access to what and who would be denied access to what. This would work perfectly fine in a small organization and a small application that hardly changes, but this may not be practical in larger scenarios. Another solution consists of creating groups of people, adding people to those groups, and then deciding what group has access to what.

In this example, we will use a field of the Employees table to identify who can have access to the form used to create a new store item.

Practical Learning: Implementing Contextual Access

Display the Switchboard.cs file

Change the file as follows:

using System;
using System.Data;
using System.Drawing;
using System.Data.OleDb;
using System.Windows.Forms;
using System.ComponentModel;

public class Switchboard : Form
{
    private Button btnStoreInventory;
    private Button btnCreateStoreItem;
    private Button btnEmployees;
    private Button btnLogInUser;
    private Button btnClose;

    private bool employeeIsAManager;

    public Switchboard()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        btnStoreInventory = new Button();
        btnCreateStoreItem = new Button();
        btnEmployees = new Button();
        btnLogInUser = new Button();
        btnClose = new Button();

        SuspendLayout();

        btnStoreInventory.Font = new Font("Georgia", 18F, FontStyle.Bold,
                                          GraphicsUnit.Point, 0);
        btnStoreInventory.Location = new Point(11, 12);
        btnStoreInventory.Size = new Size(227, 98);
        btnStoreInventory.TabIndex = 21;
        btnStoreInventory.Text = "View Store Inventory";
        btnStoreInventory.UseVisualStyleBackColor = true;
        btnStoreInventory.Click += new System.EventHandler(btnStoreInventoryClicked);

        btnCreateStoreItem.Font = new Font("Georgia", 18F, FontStyle.Bold,
                                           GraphicsUnit.Point, 0);
        btnCreateStoreItem.Location = new Point(253, 12);
        btnCreateStoreItem.Size = new Size(227, 98);
        btnCreateStoreItem.TabIndex = 23;
        btnCreateStoreItem.Text = "Create Store Item";
        btnCreateStoreItem.UseVisualStyleBackColor = true;
        btnCreateStoreItem.Click += new System.EventHandler(btnCreateStoreItemClicked);

        btnEmployees.Font = new Font("Georgia", 18F, FontStyle.Bold, GraphicsUnit.Point, 0);
        btnEmployees.Location = new Point(10, 128);
        btnEmployees.Size = new Size(227, 98);
        btnEmployees.TabIndex = 25;
        btnEmployees.Text = "Employees";
        btnEmployees.UseVisualStyleBackColor = true;
        btnEmployees.Click += new System.EventHandler(btnEmployeesClicked);

        btnLogInUser.Font = new Font("Georgia", 18F, FontStyle.Bold, GraphicsUnit.Point, 0);
        btnLogInUser.Location = new Point(254, 128);
        btnLogInUser.Size = new Size(227, 98);
        btnLogInUser.TabIndex = 24;
        btnLogInUser.Text = "Log in as a Different Employee";
        btnLogInUser.UseVisualStyleBackColor = true;
        btnLogInUser.Click += new System.EventHandler(btnLogInUserClicked);

        btnClose.Font = new Font("Georgia", 18F, FontStyle.Bold,
                                 GraphicsUnit.Point, 0);
        btnClose.Location = new Point(10, 243);
        btnClose.Size = new Size(470, 66);
        btnClose.TabIndex = 22;
        btnClose.Text = "Close Application";
        btnClose.UseVisualStyleBackColor = true;
        btnClose.Click += new System.EventHandler(btnCloseClicked);

        ClientSize = new Size(493, 323);
        Controls.Add(btnEmployees);
        Controls.Add(btnLogInUser);
        Controls.Add(btnCreateStoreItem);
        Controls.Add(btnClose);
        Controls.Add(btnStoreInventory);

        StartPosition = FormStartPosition.CenterScreen;
        Text = "Fun Department Store - Switchboard";
        Load += new System.EventHandler(SwitchboardLoaded);
        ResumeLayout(false);

    }

    private void btnStoreInventoryClicked(object sender, EventArgs e)
    {
        StoreInventory si = new StoreInventory();
        si.ShowDialog();
    }

    private void btnCloseClicked(object sender, EventArgs e)
    {
        Close();
    }

    private void LogInToTheApplication()
    {
        bool usernamePasswordMatch = false;
        bool currentEmployeeIsManager = false;
        Authenticator dlgLogIn = new Authenticator();
        string strPasswordFromDialogBox = "", strPasswordFromDatabase = "";
        string strUsernameFromDialogBox = "", strUsernameFromDatabase = "";

        // Display the Autheticator dialog box.
        // If the user clicks Cancel, simply close the application
        if (dlgLogIn.ShowDialog() == System.Windows.Forms.DialogResult.Cancel)
            Close();
        else // If the user clicks OK
        {
            // If the employee doesn't enter a username, display a message box...
            if (dlgLogIn.txtUsername.Text == "")
            {
                MessageBox.Show("You must enter a user name.",
                                "Fun Department Store",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                // ... and close the application
                Close();
            }

            // If the employee doesn't enter a password, display a message box...
            if (dlgLogIn.txtPassword.Text == "")
            {
                MessageBox.Show("You must type a password.",
                                "Fun Department Store",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                // ... and close the application
                Close();
            }

            // Get the user name of the dialog box
            strUsernameFromDialogBox = dlgLogIn.txtUsername.Text;
            // Get the password of the dialog box
            strPasswordFromDialogBox = dlgLogIn.txtPassword.Text;

            // To connect to the database, after the following Data Source= expression,
            // type \\, followed by the name of the server (ours is named Expression),
            // followed by \\, followed by the name of the folder where the database 
            // is installed (ours is named Fun Department Store) (of course, you must
            // have shared that folder), followed by \\, and followed by the name of
            // the database, in this case FunDS
            using (OleDbConnection conFunDS =
                    new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;" +
                        @"Data Source=\\Expression\\Fun Department Store\\FunDS.accdb"))
            {
                // Get the records of all employees
                OleDbCommand cmdFunDS = new OleDbCommand("SELECT * FROM Employees;", conFunDS);

                // Create a data adapater to retrieve the employees
                OleDbDataAdapter odaEmployees = new OleDbDataAdapter(cmdFunDS);
                // Create a data set of employees
                DataSet dsEmployees = new DataSet("EmployeesSet");
                // Fill the data set with the Employees records
                odaEmployees.Fill(dsEmployees);

                // Open the connection
                conFunDS.Open();

                // Navigate to each record
                for (int i = 0; i < dsEmployees.Tables[0].Rows.Count; i++)
                {
                    // Get a reference to the current record
                    DataRow rcdEmployee = dsEmployees.Tables[0].Rows[i];

                    // Get the managing status of the employee
                    currentEmployeeIsManager = bool.Parse(rcdEmployee["Manager"].ToString());
                    // When you are on a record, get the username of the employee
                    strUsernameFromDatabase = rcdEmployee["Username"].ToString();
                    // and the password
                    strPasswordFromDatabase = rcdEmployee["UserPassword"].ToString();

                    // Compare the current username to the username of the dialog box
                    // and the current password to the password of the dialog box.
                    // If they match, ...
                    if (strUsernameFromDatabase.Equals(strUsernameFromDialogBox) &&
                        strPasswordFromDatabase.Equals(strPasswordFromDialogBox))
                    {
                        usernamePasswordMatch = true;

                        // Find out whether this employee is a manager.
                        // If so, make a reference...
                        if (currentEmployeeIsManager == true)
                            employeeIsAManager = true;
                        else
                            employeeIsAManager = false;

                        // ... and stop searching
                        break;
                    }

                    // If there is no match, continue to the next record, 
                    // up to the end of the table
                }

                // If there was a match for username/password, display the Switchboard

                // If there was no match for username/password, 
                // Let the employee know ...
                if (usernamePasswordMatch == false)
                {
                    MessageBox.Show("The username and password combination did " +
                                    "not match any of the employees",
                                    "Fun Department Store",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                    // ... and close the application
                    Close();
                }
            }
        }
    }

    private void LogInAsADifferentEmployee()
    {
        bool currentEmployeeIsManager = false;
        bool usernamePasswordMatch = false;
        Authenticator dlgLogIn = new Authenticator();
        string strPasswordFromDialogBox = "", strPasswordFromDatabase = "";
        string strUsernameFromDialogBox = "", strUsernameFromDatabase = "";

        // Display the Autheticator dialog box.
        // If the user clicks Cancel, simply close the application
        if (dlgLogIn.ShowDialog() == System.Windows.Forms.DialogResult.Cancel)
            return;
        else // If the user clicks OK
        {
            // If the employee doesn't enter a username, display a message box...
            if (dlgLogIn.txtUsername.Text == "")
                MessageBox.Show("You must enter a user name.",
                                "Fun Department Store",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);

            // If the employee doesn't enter a password, display a message box...
            if (dlgLogIn.txtPassword.Text == "")
                MessageBox.Show("You must type a password.",
                                "Fun Department Store",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);

            // Get the user name of the dialog box
            strUsernameFromDialogBox = dlgLogIn.txtUsername.Text;
            // Get the password of the dialog box
            strPasswordFromDialogBox = dlgLogIn.txtPassword.Text;

            // To connect to the database, after the following Data Source= expression,
            // type \\, followed by the name of the server (ours is named Expression),
            // followed by \\, followed by the name of the folder where the database 
            // is installed (ours is named Fun Department Store) (of course, you must
            // have shared that folder), followed by \\, and followed by the name of
            // the database, in this case FunDS
            using (OleDbConnection conFunDS =
                    new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;" +
                        @"Data Source=\\Expression\\Fun Department Store\\FunDS.accdb"))
            {
                // Get the records of all employees
                OleDbCommand cmdFunDS = new OleDbCommand("SELECT * FROM Employees;", conFunDS);

                // Create a data adapater to retrieve the employees
                OleDbDataAdapter odaEmployees = new OleDbDataAdapter(cmdFunDS);
                // Create a data set of employees
                DataSet dsEmployees = new DataSet("EmployeesSet");
                // Fill the data set with the Employees records
                odaEmployees.Fill(dsEmployees);

                // Open the connection
                conFunDS.Open();

                // Navigate to each record
                for (int i = 0; i < dsEmployees.Tables[0].Rows.Count; i++)
                {
                    // Get a reference to the current record
                    DataRow rcdEmployee = dsEmployees.Tables[0].Rows[i];

                    // Get the managing status of the employee
                    currentEmployeeIsManager = bool.Parse(rcdEmployee["Manager"].ToString());
                    // When you are on a record, get the username of the employee
                    strUsernameFromDatabase = rcdEmployee["Username"].ToString();
                    // and the password
                    strPasswordFromDatabase = rcdEmployee["UserPassword"].ToString();

                    // Compare the current username to the username of the dialog box
                    // and the current password to the password of the dialog box.
                    // If they match, ...
                    if (strUsernameFromDatabase.Equals(strUsernameFromDialogBox) &&
                        strPasswordFromDatabase.Equals(strPasswordFromDialogBox))
                    {
                        usernamePasswordMatch = true;

                        // Find out whether this employee is a manager.
                        // If so, make a reference.
                        if (currentEmployeeIsManager == true)
                            employeeIsAManager = true;
                        else
                            employeeIsAManager = false;

                        // ... display the switchboard
                        break;
                    }

                    // If there is no match, continue to the next record, 
                    // up to the end of the table
                }

                // If there was a match for username/password, display the Switchboard

                // If there was no match for username/password, 
                // Let the employee know ...
                if (usernamePasswordMatch == false)
                {
                    MessageBox.Show("The username and password combination did " +
                                    "not match any of the employees",
                                    "Fun Department Store",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);

                    return;
                }
            }
        }
    }

    private void SwitchboardLoaded(object sender, EventArgs e)
    {
        employeeIsAManager = false;
        LogInToTheApplication();
    }

    private void btnCreateStoreItemClicked(object sender, EventArgs e)
    {
        CreateStoreItem csi = new CreateStoreItem();

        // Using the global canCreateStoreItem variable, find out
        // whether the current user is a manager.
        // If the user is, then display the Create Store Item form
        if (employeeIsAManager == true)
            csi.ShowDialog();
        else // If the user is not, diaplay a message box
            MessageBox.Show("You are not authorized to create store items.",
                            "Fun Department Store",
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
    }

    private void btnLogInUserClicked(object sender, EventArgs e)
    {
        LogInAsADifferentEmployee();
    }

    private void btnEmployeesClicked(object sender, EventArgs e)
    {
        Employees staff = new Employees();

        // If the user is a manager, enable the controls in the group box.
        if (employeeIsAManager == true)
            staff.grpNewEmployee.Enabled = true;
        else // Otherwise, disable them
            staff.grpNewEmployee.Enabled = false;

        staff.ShowDialog();
    }
}

public class DepartmentStore
{
    public static int Main()
    {
        Application.Run(new Switchboard());
        return 0;
    }
}

To test the application, press F5
When the dialog box comes up, click Cancel. Notice that the application did not continue
Execute the application again
When the dialog box displays, type the user name as stanley and press Enter
Type the password as Password5 and press Enter
Read the message box and press Enter
Execute the application again
Type the username as mtownsend and press Tab
Type the password as Password5 and pass Enter
Click View Store Inventory
Close the form
Click Create Store Item
Read the message and click OK
Click Log in as a Different Employees
In the username of the dialog box, type msamson and press Tab
Type the password as password16 and press Enter
Click Employees
Close the Employees form
Click Log in as a Different Employees
In the username of the dialog box, type msamson and press Tab
Type the password as Password6 and press Enter
Click Create Store Item
Enter some values for the record
Click Create
Read the message box and click OK
Close the form
Click Employees
Close the Employees form
Click Log in as a Different Employees
Click Cancel
Click Log in as a Different Employees
In the username of the dialog box, type kdavids and press Tab
Type the password as Password9 and press Enter
Click View Store Inventory
Close the form
Cick Create Store Iteam
Read the message and click OK
Close the Switchboard form