Creating the Order Processing Application

To create the Order Processing application, you need to create the classes and windows that enable customers and the administrator to use the Order Processing application.

Creating the Customers Class

The Customers.vb file defines the Customers class that provides the functions to register new customers and retrieve information on an existing customer.

Listing 2-2 shows the code for the Customers.vb file:

Listing 2-2: The Customers.vb File

 'Static Model Imports System.Data.SqlClient Public Class Customers    Public customerId As Integer    Public username As String    Public password As String    Public firstName As String    Public lastName As String    Public address1 As String    Public address2 As String    Public city As String    Public country As String    Public zipCode As String    Private ds As DataSet    Private sqlCommand As sqlCommand    Private sqlda As SqlDataAdapter    'This method registers a new customer and returns the id of the newly registered    customer    Public Function addCustomerInformation() As Integer    sqlCommand = New SqlCommand("insert into customers values('" &     username & "','" & password & "','" & firstName &     "','" & lastName & "','" & address1 & "','" & address2 &    "','" & city & "','" & country & "','" & zipCode & "' )",    sqlConnection)    sqlCommand.ExecuteNonQuery()    sqlCommand = New SqlCommand("select max(customerId) from customers", sqlConnection)    sqlda = New SqlDataAdapter(sqlCommand)    ds = New DataSet    sqlda.Fill(ds)    If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then       Return ds.Tables(0).Rows(0).Item(0)       Else       Return 0    End If    End Function    'This method retrieves the information for a specified customer    Public Sub retrieveCustomerInformation(ByVal cId As Integer)    sqlCommand = New SqlCommand("select firstname,lastname,address1,address2,    city,country,zipcode from Customers where customerId='" & cId & "'",    sqlConnection)    sqlda = New SqlDataAdapter(sqlCommand)    ds = New DataSet    sqlda.Fill(ds)    If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then       firstName = ds.Tables(0).Rows(0).Item(0)       If Not IsDBNull(ds.Tables(0).Rows(0).Item(1)) Then       lastName = ds.Tables(0).Rows(0).Item(1)       Else        lastName = ""    End If    address1 = ds.Tables(0).Rows(0).Item(2)    If Not IsDBNull(ds.Tables(0).Rows(0).Item(3)) Then       address2 = ds.Tables(0).Rows(0).Item(3)       Else        address2 = ""    End If    city = ds.Tables(0).Rows(0).Item(4)    country = ds.Tables(0).Rows(0).Item(5)    zipCode = ds.Tables(0).Rows(0).Item(6)    Else    firstName = ""    lastName = ""    address1 = ""    address2 = ""    city = ""    country = ""    zipCode = ""    End If    End Sub End Class 'END CLASS DEFINITION Customers 

 

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The above listing defines the following methods :

• addCustomerInformation() : Registers a new customer and returns the id of the newly registered customer.

• retrieveCustomerInformation() : Retrieves the information for a specific customer.

Creating the Orders Class

The Orders.vb file defines the Orders class that saves and retrieves information about the orders placed by a customer using the Place Order window.

Listing 2-3 shows the code for the Orders.vb file:

Listing 2-3: The Orders.vb File

 'Static Model Imports System.Data.SqlClient Public Class Orders    Public orderDate As Date    Public customerId As Integer    Public status As String    Public completionDate As Date    Public amount As Double    Public orderId As Integer    Dim sqlCommand As sqlCommand    Dim sqlda As SqlDataAdapter    Dim ds As DataSet    'This method saves the order in the database and returns the order Id of the newly saved order.    If this method fails to execute it returns 0       Public Function SaveOrder() As Integer       Try          sqlCommand = New SqlCommand("insert into orders(orderDate,amount,customerId,status) values('"          & orderDate & "'," & amount & "," & customerId & ",'P')", sqlConnection)          sqlCommand.ExecuteNonQuery()          sqlCommand = New SqlCommand("select max(orderId) from orders", sqlConnection)          sqlda = New SqlDataAdapter(sqlCommand)          ds = New DataSet          sqlda.Fill(ds)          If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then              Return ds.Tables(0).Rows(0).Item(0)          Else              Return 0          End If       Catch ex As Exception       Return 0    End Try    End Function    Public Sub New()    orderId = 0    End Sub    'This method retrieves the orders according to their status. This method returns an ArrayList    containing Orders objects that represents the orders placed by the customers    Public Function RetrieveOrderByStatus(ByVal strstatus As String) As ArrayList    Dim arrayOrders As New ArrayList    sqlCommand = New SqlCommand("select orderId,orderDate,amount,    customerID,completionDate from    orders where status='" & strstatus & "'", sqlConnection)    sqlda = New SqlDataAdapter(sqlCommand)    ds = New DataSet    sqlda.Fill(ds)    If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then          Dim rowCount As Integer          For rowCount = 0 To ds.Tables(0).Rows.Count - 1             Dim objOrders As New Orders             'Retrieve orderId             objOrders.orderId = ds.Tables(0).Rows(rowCount).Item(0)             'Retrieve orderDate             objOrders.orderDate = ds.Tables(0).Rows(rowCount).Item(1)             'Retrieve customer id             objOrders.customerId = ds.Tables(0).Rows(rowCount).Item(3)             'Retrieve amount             objOrders.amount = ds.Tables(0).Rows(rowCount).Item(2)             'Retrieve completion date             If Not IsDBNull(ds.Tables(0).Rows(rowCount).Item(4)) Then                objOrders.completionDate = ds.Tables(0).Rows(rowCount).Item(4)             End If           arrayOrders.Add(objOrders)    Next    Return arrayOrders    Else    'return empty arraylist    Return arrayOrders    End If    End Function    'This method retrieves the status of the order. This method returns the status as pending,    completed, or invoiced. If the status is completed then this method returns the completion date    along with the status. If the status is invoiced, this method returns the invoice id and invoice    date along with the status.    Public Function RetrieveOrderStatus(ByVal orderId As Integer) As String    sqlCommand = New SqlCommand("select status,completionDate from orders where orderId=" &    orderId & " and customerId=" & custId & "", sqlConnection)    sqlda = New SqlDataAdapter(sqlCommand)    ds = New DataSet    sqlda.Fill(ds)    If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then       If ds.Tables(0).Rows(0).Item(0) = "P" Then       Return "pending"       ElseIf ds.Tables(0).Rows(0).Item(0) = "C" Then       Return "completed;" & ds.Tables(0).Rows(0).Item(1)       Else       'Retrieve the invoice id and invoice date for the specified order       Dim objInvoices As New Invoices       Return "invoiced;" & objInvoices.retrieveInvoiceInfo(orderId)    End If    Else    Return ""    End If    End Function    'This method updates the status of the order as completed (in the database as C) or invoiced     (in the database as I) depending on the update mode.     Public Sub UpdateOrderStatus(ByVal Id As Integer, ByVal mode As String)    If mode = "completed" Then       Dim dt As System.DateTime       sqlCommand = New SqlCommand("update Orders set status='C', completiondate='" &        dt.Today & "' where orderId=" & Id & "", sqlConnection)       sqlCommand.ExecuteNonQuery()       ElseIf mode = "invoiced" Then       sqlCommand = New SqlCommand("update Orders set status='I' where orderId=" &       Id & "", sqlConnection)       sqlCommand.ExecuteNonQuery()    End If  End Sub End Class 'END CLASS DEFINITION Orders 

 

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The above listing defines the following methods:

• SaveOrder() : Saves the order in the Orders table and returns the order id of the newly saved order.

• RetrieveOrderByStatus() : Accepts the order id as a parameter and retrieves the order status whether it is pending, completed, or invoiced.

• UpdateOrderStatus() : Accepts the order id and status mode as parameters and updates the order according to the status mode. This method updates the order status as ˜C if the status mode is ˜completed and ˜I if the status mode is ˜invoiced .

Creating the OrderInformation Class

The OrderInformation.vb file defines the OrderInformation class that saves and retrieves information about the products in an order that a customer places using the Place Order window.

Listing 2-4 shows the code for the OrderInformation.vb file:

Listing 2-4: The OrderInformation.vb File

 'Static Model Imports System.Data.SqlClient Public Class OrderInformation    Public orderId As Integer    Public productId As Integer    Public quantity As Integer    Dim sqlCommand As sqlCommand    Dim sqlda As SqlDataAdapter    Dim ds As DataSet    'This method saves the product wise order information    Public Sub SaveOrderInfo()    Try       sqlCommand = New SqlCommand("insert into OrderInformation values(" & orderId       &       "," & productId & "," & quantity & ")", sqlConnection)       sqlCommand.ExecuteNonQuery()       Catch ex As Exception    End Try    End Sub    'This method retrieves the product wise information for an order    Public Function RetrieveOrderInfo(ByVal Id As Integer) As ArrayList    Dim objOrderInformation As New ArrayList    sqlCommand = New SqlCommand("select OrderId,ProductId,sum(qty) as total from    OrderInformation    where OrderId=" & Id & "  group by OrderId,ProductId", sqlConnection)    sqlda = New SqlDataAdapter(sqlCommand)    ds = New DataSet    sqlda.Fill(ds)    If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then       Dim rowcount As Integer       For rowcount = 0 To ds.Tables(0).Rows.Count - 1          Dim tempObjOrderInformation As New OrderInformation          tempObjOrderInformation.orderId = Id          'Retrieve product id          tempObjOrderInformation.productId = ds.Tables(0).Rows(rowcount).Item(1)          'Retrieve quantity ordered for that product          tempObjOrderInformation.quantity = ds.Tables(0).Rows(rowcount).Item(2)          objOrderInformation.Add(tempObjOrderInformation)       Next    End If    Return objOrderInformation    End Function End Class 'END CLASS DEFINITION OrderInformation 

 

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The above listing defines the following methods:

• SaveOrderInfo() : Saves the product information provided in an order, such as the product id and quantity of that product.

• RetrieveOrderInfo() : Accepts the order id and returns product information for the order referenced by that order id.

Creating the Invoices Class

The Invoices.vb file defines the Invoices class that saves and retrieves information about the invoice that the administrator generates using the Invoice window.

Listing 2-5 shows the code for the Invoices.vb file:

Listing 2-5: The Invoices.vb File

 'Static Model Imports System.Data.SqlClient Public Class Invoices    Public invoiceId As Integer    Public invoiceDate As Date    Public orderId As Integer    Public customerId As Integer    Public subTotal As Double    Public paymentMode As String    Public shipping_handlingCost As Double    Public totalAmount As Double    Private sqlCommand As sqlCommand    Private sqlda As SqlDataAdapter    Private ds As DataSet    'This method generates the invoice    Public Sub generateInvoice()               sqlCommand = New SqlCommand("insert into Invoices values('" & invoiceDate & "',"       & orderId & "," & customerId & "," & subTotal & "," &       shipping_handlingCost & "," & totalAmount & ",'" & paymentMode &       "')",       sqlConnection)       sqlCommand.ExecuteNonQuery()    End Sub    'This method returns the combination of Invoice Id and invoice date as string for the specified    order    Public Function retrieveInvoiceInfo(ByVal Id As Integer) As String    sqlCommand = New SqlCommand("select invoiceId,invoiceDate from invoices where orderId=" &    Id & "", sqlConnection)    sqlda = New SqlDataAdapter(sqlCommand)    ds = New DataSet    sqlda.Fill(ds)    If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then       Return ds.Tables(0).Rows(0).Item(0) & ";" & ds.Tables(0).Rows(0).Item(1)       Else       Return ""    End If    End Function    'This method returns the Invoice Id of the last invoice raised    Public Function retrieveInvoiceId() As Integer    sqlCommand = New SqlCommand("select max(invoiceId) from invoices", sqlConnection)    sqlda = New SqlDataAdapter(sqlCommand)    ds = New DataSet    sqlda.Fill(ds)    If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then       Return ds.Tables(0).Rows(0).Item(0)       Else       Return 0    End If    End Function End Class 'END CLASS DEFINITION Invoices 

 

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The above listing defines the following methods:

• generateInvoice() : Generates a new invoice and stores the invoice information in the Invoices table.

• retrieveInvoiceInfo() : Accepts the order id as a parameter and returns the combination of an invoice id and invoice date as a string that corresponds to the order id.

• retrieveInvoiceId() : Retrieves the invoice id of the last invoice generated.

Creating the InvoiceCreditCardInfo Class

The Invoices.vb file defines the InvoiceCreditCardInfo class that saves the credit card information of a customer that the administrator specifies using the Invoice window.

Listing 2-6 shows the code for the InvoiceCreditCardInfo.vb file:

Listing 2-6: The InvoiceCreditCardInfo.vb File

 'Static Model Imports System.Data.SqlClient Public Class InvoiceCreditCardInfo    Public invoiceId As Integer    Public nameOnCard As String    Public creditCardNumber As String    Private sqlCommand As sqlCommand       Public Sub New(ByVal invoiceId As Integer, ByVal nameOnCard As String, ByVal creditCardNumber As String)       Me.invoiceId = invoiceId       Me.nameOnCard = nameOnCard       Me.creditCardNumber = creditCardNumber    End Sub    'This method saves the credit card information of the customer.    Public Sub saveCreditCardInfo()       sqlCommand = New SqlCommand("insert into InvoiceCreditCardInfo values(" & invoiceId       &       ",'" & nameOnCard & "','" & creditCardNumber & "')", sqlConnection)       sqlCommand.ExecuteNonQuery()    End Sub End Class  'END CLASS DEFINITION InvoiceCreditCardInfo 

 

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In the above listing, the saveCreditCardInfo method saves the customer s credit card information into the InvoiceCreditCardInfo table.

Creating the Shared Module

The Shared.vb file defines the Shared module that provides the main() function to initiate the Order Processing application.

Listing 2-7 shows the code for the Shared.vb file:

Listing 2-7: The Shared.vb File

 Imports System.Data.SqlClient Imports System.IO Module _Shared    'A variable to store the login role. The role can be of administrator or customer.    Public loginRole As String    'Stores the id of the customer     Public custId As Integer    'A boolean variable that keeps in track the success and failure of invoice generation process    Public boolInvoiceGeneration As Boolean    Dim strSqlConnection As String    Public sqlConnection As New sqlConnection    Public Sub main()       'Try to establish connection with database OrderProcessing through SQLClient Connection object       Try       Try          'Read connection string from a text file settings,text located in /bin folder of the application          Dim sr As New StreamReader("Settings.txt")          strSqlConnection = sr.ReadLine          sr.Close()          Catch ex As Exception          'If file settings.txt not found          strSqlConnection = "SERVER=localhost;UID=sa;PWD=sa;Initial          Catalog=OrderProcessing"       End Try       sqlConnection.ConnectionString = strSqlConnection       sqlConnection.Open()       Dim objLoginManager As New LoginManager       objLoginManager.ShowDialog()       Catch ex As Exception       MsgBox("Error in establishing connection", MsgBoxStyle.OKOnly, "CONNECTION ERROR")       Exit Sub       End Try    End Sub End Module 

 

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In the above listing, the main() function establishes a connection with the OrderProcessing database through a SqlConnection object and invokes the Login Manager window.

Creating the Login Manager Window

The LoginManager class defines the Login Manager window. The LoginManager class enables a customer to specify the login credentials to place an order. The LoginManager class also enables a new customer to register.

Listing 2-8 shows the code for the frmLoginManager.vb that defines the LoginManager class:

Listing 2-8: The frmLoginManager.vb File

 Imports System.Data.SqlClient Imports System.IO Public Class LoginManager    Inherits System.Windows.Forms.Form    Dim strSqlConnection As String    Dim ds As DataSet    Dim sqlda As SqlDataAdapter    Dim sqlCommand As sqlCommand    Private Sub cmdGo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles       cmdGo.Click       'Verifying the login credentials        Try          sqlCommand = New SqlCommand("select customerId from Customers where username='" &          txtUserName.Text & "' and password='" & txtPassWord.Text & "'", sqlConnection)          sqlda = New SqlDataAdapter(sqlCommand)          ds = New DataSet          sqlda.Fill(ds)          Catch ex As Exception          MsgBox("Error in login.", MsgBoxStyle.OKOnly, "LOGIN ERROR")          txtUserName.Focus()          Exit Sub       End Try       'To check whether the login attempt is successful       If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then          If txtUserName.Text = "administrator" Then           loginRole = "administrator"          Else           loginRole = "customer"          End If       custId = ds.Tables(0).Rows(0).Item(0)       'An object reference to the ApplicationManager class       Dim objApplicationManager As New ApplicationManager       objApplicationManager.ShowDialog()       txtUserName.Text = ""       txtPassWord.Text = ""       Else       MsgBox("Login Unsuccessful.", MsgBoxStyle.OKOnly, "INVALID LOGIN CREDENTIALS")       txtUserName.Focus()       Exit Sub       End If    End Sub    Private Sub cmdRegister_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)       Handles cmdRegister.Click       Dim objCustomerRegisteration As New CustomerRegistration       objCustomerRegisteration.ShowDialog()       If Not custId = 0 Then       loginRole = "customer"       txtUserName.Text = ""       txtPassWord.Text = ""       'An object reference to the ApplicationManager class       Dim objApplicationManager As New ApplicationManager       objApplicationManager.ShowDialog()       End If    End Sub End Class 

 

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The above listing defines the following methods:

• cmdGo_Click() : Executes when a customer specifies the user name and password and clicks the Login button. This method checks for the validity of the login information and invokes the Application Manager window if the login information is correct.

• cmdRegister_Click() : Executes when a prospective customer clicks the New User Sign In Here button to register and obtain access to the Place Order window. This method invokes the Customer Registration window.

Figure 2-4 shows the output of Listing 2-8:

Figure 2-4: The Login Manager Window

Creating the Application Manager Window

The ApplicationManager class defines the Application Manager window that enables a customer to access the Place Order and the View Order Status windows, and enables an administrator to access the Update Order Status and the Raise Invoice windows.

Listing 2-9 shows the code for the frmApplicationManager.vb that defines the ApplicationManager class:

Listing 2-9: The frmApplicationManager.vb File

 Public Class ApplicationManager Inherits System.Windows.Forms.Form Private Sub ApplicationManager_Load(ByVal sender As System.Object, ByVal e As _ System.EventArgs) Handles MyBase.Load       If loginRole = "administrator" Then       mnuItemUpdateOrder.Enabled = True       mnuitemInvoice.Enabled = True       mnuViewOrderStatus.Enabled = False       mnuPlaceOrder.Enabled = False       Else       mnuItemUpdateOrder.Enabled = False       mnuitemInvoice.Enabled = False       mnuViewOrderStatus.Enabled = True       mnuPlaceOrder.Enabled = True       End If    End Sub       Private Sub MenuItem6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _ Handles MenuItem6.Click       Dim objPlaceOrder As New PlaceOrder       objPlaceOrder.ShowDialog()    End Sub       Private Sub MenuItem1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem1.Click       Dim objViewOrderStatus As New ViewOrderStatus       objViewOrderStatus.ShowDialog()    End Sub       Private Sub mnuItemUpdateOrder_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)       Handles mnuItemUpdateOrder.Click       Dim objUpdateOrderStatus As New UpdateOrderStatus       objUpdateOrderStatus.ShowDialog()    End Sub       Private Sub MenuItem4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem4.Click       Dim objRaiseInvoice As New RaiseInvoice       objRaiseInvoice.ShowDialog()    End Sub End Class 

 

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The above listing defines the following methods:

• MenuItem6_Click() : Executes when a customer selects the Orders->Place Order option to place orders. This method invokes the Place Order window.

• MenuItem1_Click() : Executes when a customer selects the Orders->View Order Status option to view the status of orders. This method invokes the View Order Status window.

• mnuItemUpdateOrder_Click() : Executes when the administrator selects the Orders->Update Order option to update the status of orders. This method invokes the Update Order Status window.

• MenuItem4_Click() : Executes when the administrator selects the Invoice->Raise Invoice option to raise invoices for completed orders. This method invokes the Raise Invoice window.

Figure 2-5 shows the output of Listing 2-9:

Figure 2-5: The Application Manager Window

The customer uses the Orders menu to place orders and view the status of orders. The administrator uses the Orders menu to update the status of orders and uses the Invoices menu to raise the invoices for completed orders.

Creating the Place Order Window

The PlaceOrder class defines the Place Order window. The PlaceOrder class displays the available products and enables a customer to select products and place an order.

Listing 2-10 shows the code for the frmPlaceOrder.vb that defines the PlaceOrder class:

Listing 2-10: The frmPlaceOrder.vb File

 Imports System.Data.SqlClient Public Class PlaceOrder    Inherits System.Windows.Forms.Form    Dim ds As DataSet    Dim sqlda As SqlDataAdapter    Dim sqlCommand As sqlCommand    Dim tempListViewItem As ListViewItem    Private Sub PlaceOrder_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)     Handles MyBase.Load    'Retrieve product list from the database.    Try       sqlCommand = New SqlCommand("select product from products", sqlConnection)       sqlda = New SqlDataAdapter(sqlCommand)       ds = New DataSet       sqlda.Fill(ds)       Catch ex As Exception       MsgBox("Unable to retrieve products.", MsgBoxStyle.OKOnly, "Retrieval Error")       Exit Sub    End Try    If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then       Dim rowcount As Integer       For rowcount = 0 To ds.Tables(0).Rows.Count - 1          productCombo.Items.Add(ds.Tables(0).Rows(rowcount).Item(0))       Next       productCombo.SelectedIndex = 0       Else       MsgBox("No product found.", MsgBoxStyle.OKOnly, "First update product information")       Exit Sub    End If    End Sub    Private Sub productCombo_SelectedIndexChanged(ByVal sender As Object, ByVal e As       System.EventArgs) Handles productCombo.SelectedIndexChanged       If Not productCombo.Text = "" Then          'Retrieve quantity available and unit price of the selected product.          Try             sqlCommand = New SqlCommand("select unitPrice,qtyInHand from products where product='"             &             productCombo.Text & "'", sqlConnection)             sqlda = New SqlDataAdapter(sqlCommand)             ds = New DataSet             sqlda.Fill(ds)             If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then                txtUnitPrice.Text = ds.Tables(0).Rows(0).Item(0)                Dim itemCount As Integer                Dim qtyAvailable As Integer = ds.Tables(0).Rows(0).Item(1)                For itemCount = 0 To listviewOrder.Items.Count - 1                   If listviewOrder.Items(itemCount).Text = productCombo.Text Then                   qtyAvailable = qtyAvailable -                   Integer.Parse(listviewOrder.Items(itemCount).SubItems(1).Text)                End If                Next             txtQuantityAvailable.Text = qtyAvailable             End If             Catch ex As Exception             MsgBox("Unable to retrieve information for the selected product.", MsgBoxStyle.OKOnly,             "Retrieval Error")             Exit Sub          End Try       End If    End Sub    Private Sub txtQuantity_KeyPress(ByVal sender As Object, ByVal e As       System.Windows.Forms.KeyPressEventArgs) Handles txtQuantity.KeyPress       If Not Char.IsDigit(e.KeyChar) Then          If e.KeyChar = vbBack Then          Exit Sub       End If       e.Handled = True       End If    End Sub       Private Sub cmdAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdAdd.Click       If Not productCombo.Text = "" And Not txtQuantity.Text = "" And Not txtQuantity.Text = "0"          Then          If Double.Parse(txtQuantity.Text) > Double.Parse(txtQuantityAvailable.Text) Then             MsgBox("Order quantity cannot be greater than available quantity.", MsgBoxStyle.OKOnly, "Please             check the value")             txtQuantity.Focus()             Exit Sub          End If          'Add the product into the listviewOrder as listviewOrder displays the products in your current order          tempListViewItem = listviewOrder.Items.Add(productCombo.Text)          tempListViewItem.SubItems.Add(txtQuantity.Text)          tempListViewItem.SubItems.Add(Double.Parse(txtUnitPrice.Text) * Double.Parse(txtQuantity.Text))          txtQuantityAvailable.Text = Integer.Parse(txtQuantityAvailable.Text) -          Integer.Parse(txtQuantity.Text)          Dim itemCount As Integer          Dim dblTotalAmount As Double          For itemCount = 0 To listviewOrder.Items.Count - 1             dblTotalAmount = dblTotalAmount +             Double.Parse(listviewOrder.Items(itemCount).SubItems(2).Text)          Next          txtAmount.Text = dblTotalAmount          txtQuantity.Text = ""          productCombo.Focus()       End If    End Sub       Private Sub cmdPlaceOrder_Click(ByVal sender As System.Object, ByVal e As _       System.EventArgs) Handles cmdPlaceOrder.Click       If Not listviewOrder.Items.Count = 0 Then          Dim dt As System.DateTime          'Creating an object of type Orders          Dim objOrders As New Orders          objOrders.customerId = custId          objOrders.amount = Double.Parse(txtAmount.Text)          objOrders.orderDate = dt.Today          'Call the SaveOrder method of Orders class to save the order          Dim orderId As Integer = objOrders.SaveOrder          'If the order is successfully saved then          If orderId <> 0 Then          Try             Dim itemCount As Integer             For itemCount = 0 To listviewOrder.Items.Count - 1                'Save the product wise order information into the database                Dim objOrderInformation As New OrderInformation                objOrderInformation.orderId = orderId                'Retrieve the product Id of the selected product                sqlCommand = New SqlCommand("select productId from products where product='" &                listviewOrder.Items(itemCount).Text & "'", sqlConnection)                sqlda = New SqlDataAdapter(sqlCommand)                ds = New DataSet                sqlda.Fill(ds)                objOrderInformation.productId = ds.Tables(0).Rows(0).Item(0)                objOrderInformation.quantity = Integer.Parse(listviewOrder.Items(itemCount).SubItems(1).Text)                'Call the SaveOrderInfo method of OrderInformantion class to save the product wise information                of the order                objOrderInformation.SaveOrderInfo()                'Update the product quantity                sqlCommand = New SqlCommand("update products set qtyInHand=qtyInHand-" &                Integer.Parse(listviewOrder.Items(itemCount).SubItems(1).Text) & " where product='" &                listviewOrder.Items(itemCount).Text & "'", sqlConnection)                sqlCommand.ExecuteNonQuery()             Next             Catch ex As Exception             MsgBox("Your order cannot be saved.", MsgBoxStyle.OKOnly, "Database Error")             Exit Sub          End Try          Else          MsgBox("Your order cannot be saved.", MsgBoxStyle.OKOnly, "Database Error")          Exit Sub       End If       MsgBox("Your order is saved successfully. Your ORDER ID is " & orderId & ".", MsgBoxStyle.OKOnly, "Success")       listviewOrder.Items.Clear()       txtAmount.Text = ""       productCombo.Focus()       End If       End Sub          Private Sub cmdClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdClose.Click          Me.Close()    End Sub End Class 

 

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The above listing defines the following methods:

• PlaceOrder_Load() : Retrieves the available products from the database and displays the products in the productCombo drop-down list box.

• cmdAdd_Click() : Executes when a customer selects a product, specifies the quantity, and clicks the Add to Order button to add the selected product in the current order. This method adds the selected product in the listviewOrder list view control that represents the current order.

• cmdPlaceOrder_Click() : Executes when a customer clicks the Place Order button to place an order for the selected products. This method calls the SaveOrder() method of the Orders class to save the order information, such as the order date, customer id, and total amount. It then calls the SaveOrderInfo() method of the OrderInformation class to save the product information, such as the product id and the quantity for that product in the order.

Figure 2-6 shows the output of Listing 2-10:

Figure 2-6: The Place Order Window

Creating the View Order Status Window

The ViewOrderStatus class defines the View Order Status window. The ViewOrderStatus class enables a customer to view the status of an order.

Listing 2-11 shows the code for the frmViewOrderStatus.vb that defines the ViewOrderStatus class:

Listing 2-11: The frmViewOrderStatus.vb File

 Imports System.Data.SqlClient Public Class ViewOrderStatus    Inherits System.Windows.Forms.Form    Dim ds As DataSet    Dim sqlda As SqlDataAdapter    Dim sqlCommand As sqlCommand    Private Sub txtOrderId_KeyPress(ByVal sender As Object, ByVal e As       System.Windows.Forms.KeyPressEventArgs) Handles txtOrderId.KeyPress       If Not Char.IsDigit(e.KeyChar) Then          If e.KeyChar = vbBack Then          Exit Sub       End If       e.Handled = True       End If    End Sub       Private Sub cmdViewStatus_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdViewStatus.Click       If Not txtOrderId.Text = "" Then          Dim strStatus As String          Try          Dim objOrders As New Orders          strStatus = objOrders.RetrieveOrderStatus(txtOrderId.Text)          If strStatus = "" Then             MsgBox("Invalid OrderId", MsgBoxStyle.OKOnly, "Please check the orderId")               Exit Sub       End If       If strStatus = "pending" Then          lblStatus.Text = "Your order referenced by Order Id " & txtOrderId.Text & "          is being processed."          Else          Dim tempArray() As String          tempArray = strStatus.Split(";")          'If the status of the order is completed then show the completion date             If tempArray(0) = "completed" Then             lblStatus.Text = "Your order has been processed. Completion date for your order is " &             tempArray(1) & "."             Else             'If the status of the order is invoiced then show the invoice id and invoice date             lblStatus.Text = "Your invoice for this order has been generated. Invoice Id is " &             tempArray(1) & " and date of generation is " & tempArray(2) & "."          End If          End If       Catch ex As Exception       MsgBox("Unable to view the order status", MsgBoxStyle.OKOnly, "Database Error")       End Try       End If       End Sub       Private Sub cmdClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles       cmdClose.Click       Me.Close()    End Sub End Class 

 

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In the above listing, the cmdViewStatus_Click() method executes when a customer specifies an order id and clicks the View Status button to view the status of the order referred to by that order id. This method calls the RetrieveOrderStatus() method of the Orders class to retrieve the status and displays the retrieved status in the lblStatus label.

Figure 2-7 shows the output of Listing 2-11:

Figure 2-7: The View Order Status Window

Creating the Update Order Status Window

The UpdateOrderStatus class defines the Update Order Status window. The UpdateOrderStatus class displays all pending orders and enables the administrator to update the status of pending orders as completed.

Listing 2-12 shows the code for the frmUpdateOrderStatus.vb that defines the UpdateOrderStatus class:

Listing 2-12: The frmUpdateOrderStatus.vb File

 Imports System.Data.SqlClient Public Class UpdateOrderStatus    Inherits System.Windows.Forms.Form    Dim tempListViewItem As ListViewItem    Dim sqlCommand As sqlCommand    Dim sqlda As SqlDataAdapter    Dim ds As DataSet       Private Sub cmdUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _          Handles cmdUpdate.Click          If Not listviewOrders.SelectedItems.Count = 0 Then             'Update the status of the order as completed             Dim dt As System.DateTime             Try                Dim objOrders As New Orders                'Call the UpdateOrderStatus method of the class Orders to update the status of _                the selected order as completed                objOrders.UpdateOrderStatus(listviewOrders.SelectedItems(0).Text, "completed")                listviewOrders.Items.Remove(listviewOrders.SelectedItems(0))                Catch ex As Exception                MsgBox("Unable to update the status of the selected order.", MsgBoxStyle.OKOnly, "Database Error")                Exit Sub             End Try          End If    End Sub          Private Sub UpdateOrderStatus_Load(ByVal sender As Object, ByVal e As System.EventArgs) _  Handles MyBase.Load          'An arraylist object to hold the order objects passed by RetrieveOrderByStatus method of Orders class          Dim arrayOrders As ArrayList          Try             Dim objOrders As New Orders             arrayOrders = objOrders.RetrieveOrderByStatus("P")             If Not arrayOrders.Count = 0 Then                Dim cnt As Integer                For cnt = 0 To arrayOrders.Count - 1                   Dim tempObjOrders As Orders                   tempObjOrders = arrayOrders(cnt)                   tempListViewItem = listviewOrders.Items.Add(tempObjOrders.orderId)                   tempListViewItem.SubItems.Add(tempObjOrders.orderDate)                   'Retrieving the customer name                   sqlCommand = New SqlCommand("select firstname, lastname from customers where customerId=" &                   tempObjOrders.customerId & "", sqlConnection)                   sqlda = New SqlDataAdapter(sqlCommand)                   ds = New DataSet                   sqlda.Fill(ds)                   If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then                      tempListViewItem.SubItems.Add(ds.Tables(0).Rows(0).Item(0) & " " &                      ds.Tables(0).Rows(0).Item(1))                      Else                      tempListViewItem.SubItems.Add("")                   End If                tempListViewItem.SubItems.Add(tempObjOrders.amount)                Next             Else             MsgBox("No orders are pending.", MsgBoxStyle.OKOnly, "No orders to be completed")             Exit Sub             End If             Catch ex As Exception             MsgBox("Unable to retrieve pending orders.", MsgBoxStyle.OKOnly, "Retrieval Error")             Exit Sub       End Try    End Sub       Private Sub cmdClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdClose.Click       Me.Close()    End Sub       Private Sub cmdViewInformation_Click(ByVal sender As System.Object, ByVal e As _ System.EventArgs)       Handles cmdViewInformation.Click       'Retrieve product wise information for the selected order.       If Not listviewOrders.SelectedItems.Count = 0 Then          Dim objViewOrderInfo As New ViewOrderInfo(listviewOrders.SelectedItems(0).Text)          objViewOrderInfo.ShowDialog()       End If    End Sub End Class 

 

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The above listing defines the following methods:

• UpdateOrderStatus_Load() : Calls the RetrieveOrderByStatus() method of the Orders class to retrieve the pending orders and displays the order information in the listViewOrders list view control.

• cmdViewInformation_Click() : Executes when the administrator selects an order from listViewOrders and clicks the View Information button to view the product information for the selected order. This method invokes the View Order Information window that displays the product information.

• cmdUpdate_Click() : Executes when the administrator selects an order from the listViewOrders list view control and clicks the Update Order button to update the status of the order as completed. This method calls the UpdateOrderStatus() method of the Orders class to update the status.

Figure 2-8 shows the output of Listing 2-12:

Figure 2-8: The Update Order Status Window

Creating the View Order Information Window

The ViewOrderInfo class defines the View Order Information window. The ViewOrderInfo class displays the products and the quantities required for a specific order.

Listing 2-13 shows the code for the frmViewOrderInfo.vb that defines the ViewOrderInfo class:

Listing 2-13: The frmViewOrderInfo.vb File

 'This class displays the product wise information for an order Imports System.Data.SqlClient Public Class ViewOrderInfo    Inherits System.Windows.Forms.Form    Dim sqlCommand As sqlCommand    Dim sqlda As SqlDataAdapter    Dim ds As DataSet    Dim orderId As Integer    Public Sub New(ByVal id As Integer)       MyBase.New()       InitializeComponent()       orderId = id    End Sub    Dim tempListViewItem As ListViewItem       Private Sub cmdClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdClose.Click       Me.Close()    End Sub       Private Sub ViewOrderInfo_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load       'An arraylist object to hold the OrderInformation objects passed by RetrieveOrderInfo _       method of OrderInformation class.       Dim arrayOrderInformation As ArrayList       Dim objOrderInformation As New OrderInformation       Try          arrayOrderInformation = objOrderInformation.RetrieveOrderInfo(orderId)          If Not arrayOrderInformation.Count = 0 Then             Dim cnt As Integer             For cnt = 0 To arrayOrderInformation.Count - 1                Dim tempObjOrderInformation As OrderInformation                tempObjOrderInformation = arrayOrderInformation(cnt)                tempListViewItem = listviewOrders.Items.Add(tempObjOrderInformation.orderId)                'Retrieving the product name                sqlCommand = New SqlCommand("select product from products where productId=" &                tempObjOrderInformation.productId & "", sqlConnection)                sqlda = New SqlDataAdapter(sqlCommand)                ds = New DataSet                sqlda.Fill(ds)                If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then                   tempListViewItem.SubItems.Add(ds.Tables(0).Rows(0).Item(0))                   Else                   tempListViewItem.SubItems.Add("")                End If                tempListViewItem.SubItems.Add(tempObjOrderInformation.quantity)             Next          End If          Catch ex As Exception          MsgBox("Unable to retrieve order information.", MsgBoxStyle.OKOnly, "Retrieval Error")          Me.Close()       End Try    End Sub End Class 

 

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In the above listing, the ViewOrderInfo_Load() method calls the RetrieveOrderInfo() method of the Orders class to retrieve the product information for the order and displays the information in the listviewOrders list view control.

Figure 2-9 shows the output of Listing 2-13:

Figure 2-9: The View Order Information Window

Creating the Raise Invoice Window

The RaiseInvoice class defines the Raise Invoice window. The RaiseInvoice class displays all the orders that have been completed and enables the administrator to select an order and raise an invoice for that order.

Listing 2-14 shows the code for the frmRaiseInvoice.vb that defines the RaiseInvoice class:

Listing 2-14: The frmRaiseInvoice.vb File

 Imports System.Data.SqlClient Public Class RaiseInvoice    Inherits System.Windows.Forms.Form    Dim sqlCommand As sqlCommand    Dim sqlda As SqlDataAdapter    Dim ds As DataSet    Dim tempListViewItem As ListViewItem       Private Sub cmdClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdClose.Click       Me.Close()    End Sub       Private Sub RaiseInvoice_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load       'An arraylist object to hold the order objects passed by RetrieveOrderByStatus method of Orders class       Dim arrayOrders As ArrayList       Try          Dim objOrders As New Orders          'Call the RetrieveOrderByStatus method to retrieve all completed orders           arrayOrders = objOrders.RetrieveOrderByStatus("C")          If Not arrayOrders.Count = 0 Then             Dim cnt As Integer             For cnt = 0 To arrayOrders.Count - 1                Dim tempObjOrders As Orders                tempObjOrders = arrayOrders(cnt)                tempListViewItem = listviewOrders.Items.Add(tempObjOrders.orderId)                tempListViewItem.SubItems.Add(tempObjOrders.orderDate)                tempListViewItem.SubItems.Add(tempObjOrders.customerId)                'Retrieving the customer name                sqlCommand = New SqlCommand("select firstname, lastname from customers where                customerId=" & tempObjOrders.customerId & "", sqlConnection)                sqlda = New SqlDataAdapter(sqlCommand)                ds = New DataSet                sqlda.Fill(ds)                If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then                   tempListViewItem.SubItems.Add(ds.Tables(0).Rows(0).Item(0) & " "                   & ds.Tables(0).Rows(0).Item(1))                   Else                   tempListViewItem.SubItems.Add("")                End If                tempListViewItem.SubItems.Add(tempObjOrders.completionDate)             Next             Else             MsgBox("No orders are left to be invoiced.", MsgBoxStyle.OKOnly, "No orders left")             Me.Close()          End If          Catch ex As Exception          MsgBox("Unable to retrieve completed orders.", MsgBoxStyle.OKOnly, "Retrieval Error")          Me.Close()       End Try    End Sub       Private Sub cmdRaise_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdRaise.Click       If Not listviewOrders.SelectedItems.Count = 0 Then          Dim objInvoice As New Invoice(listviewOrders.SelectedItems(0).Text, _          listviewOrders.SelectedItems(0).SubItems(2).Text)          objInvoice.ShowDialog()       End If       'If invoice generation was a success          If boolInvoiceGeneration = True Then          'Update the status of the selected order to invoiced(I)          Dim objOrders As New Orders          objOrders.UpdateOrderStatus(listviewOrders.SelectedItems(0).Text, "invoiced")          listviewOrders.Items.Remove(listviewOrders.SelectedItems(0))       End If    End Sub End Class 

 

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The above listing defines the following methods:

• RaiseInvoice_Load() : Calls the RetrieveOrderByStatus() method of the Orders class to retrieve information about the orders that have been completed and displays the information in the listviewOrders list view control.

• cmdRaise_Click() : Executes when the administrator selects an order and clicks the Raise button to raise an invoice for the selected order. This method invokes the Invoice window.

Figure 2-10 shows the output of Listing 2-14:

Figure 2-10: The Raise Invoice Window

Creating the Invoice Window

The Invoice class defines the Invoice window. The Invoice class displays the order, customer, and company information and enables the administrator to generate the invoice for an order selected from the Raise Invoice window.

Listing 2-15 shows the code for the frmInvoice.vb that defines the Invoice class:

Listing 2-15: The frmInvoice.vb File

 Imports System.Data.SqlClient Public Class Invoice    Inherits System.Windows.Forms.Form    Dim sqlCommand As sqlCommand    Dim sqlda As SqlDataAdapter    Dim ds As DataSet    Dim orderId As Integer    Dim customerId As Integer    Dim tempListViewItem As ListViewItem    Dim invoiceId As Integer    Public Sub New(ByVal oId As Integer, ByVal cId As Integer)       MyBase.New()       InitializeComponent()       orderId = oId       customerId = cId    End Sub         Private Sub Invoice_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _       Handles MyBase.Load       Dim dt As System.DateTime       dtPicker.Value = dt.Today       'Retrieve the invoice id of the last invoice generated       Try          Dim objInvoices As New Invoices          invoiceId = objInvoices.retrieveInvoiceId() + 1          Catch ex As Exception          invoiceId = 1       End Try       lblInvoiceId.Text = lblInvoiceId.Text & " " & invoiceId       lblOrderId.Text = lblOrderId.Text & " " & orderId       'Retrieve company information        Try          sqlCommand = New SqlCommand("select * from Company", sqlConnection)          sqlda = New SqlDataAdapter(sqlCommand)          ds = New DataSet          sqlda.Fill(ds)          If Not ds.Tables(0).Rows.Count = 0 Then             lblCompanyName.Text = lblCompanyName.Text & " : " & _             ds.Tables(0).Rows(0).Item(0)             lblCompanyAddress.Text = lblCompanyAddress.Text & " : " & _             ds.Tables(0).Rows(0).Item(1)             & ",  " & ds.Tables(0).Rows(0).Item(2) & ",  " & _             ds.Tables(0).Rows(0).Item(3)             & ",  " & ds.Tables(0).Rows(0).Item(4)             lblCompanyPhone.Text = lblCompanyPhone.Text & " : " & _             ds.Tables(0).Rows(0).Item(5)          End If          Catch ex As Exception          MsgBox("Unable to retrieve company information.", MsgBoxStyle.OKOnly, "Retrieval Error")          Me.Close()       End Try       'Retrieve Customer Information       Try          Dim objCustomers As New Customers          objCustomers.retrieveCustomerInformation(customerId)          If objCustomers.firstName = "" Then             MsgBox("Customer information not found.", MsgBoxStyle.OKOnly, "Retrieval Error")             Me.Close()             Else             lblCustomerName.Text = lblCustomerName.Text & " : " & objCustomers.firstName & " "             & objCustomers.lastName             lblAddress.Text = lblAddress.Text & " : " & objCustomers.address1 & " " _  & objCustomers.address2             lblCity.Text = lblCity.Text & " : " & objCustomers.city             lblCountry.Text = lblCountry.Text & " : " & objCustomers.country             lblZipCode.Text = lblZipCode.Text & " : " & objCustomers.zipCode          End If          Catch ex As Exception          MsgBox("Unable to retrieve customer information.", MsgBoxStyle.OKOnly, "Retrieval Error")          Me.Close()       End Try       'Retrieve Order Information. An arraylist object to hold the OrderInformation objects passed by       RetrieveOrderInfo method of OrderInformation class.       Dim arrayOrderInformation As ArrayList       Dim objOrderInformation As New OrderInformation       Try          arrayOrderInformation = objOrderInformation.RetrieveOrderInfo(orderId)          If Not arrayOrderInformation.Count = 0 Then             Dim cnt As Integer             'A variable to calculate total billing amount for the order             Dim dblTotalAmount As Double = 0             For cnt = 0 To arrayOrderInformation.Count - 1                Dim tempObjOrderInformation As OrderInformation                tempObjOrderInformation = arrayOrderInformation(cnt)                'Retrieving the product name                sqlCommand = New SqlCommand("select product,unitPrice from products where productId=" &                tempObjOrderInformation.productId & "", sqlConnection)                sqlda = New SqlDataAdapter(sqlCommand)                ds = New DataSet                sqlda.Fill(ds)                If Not ds.Tables.Count = 0 And Not ds.Tables(0).Rows.Count = 0 Then                tempListViewItem = listviewOrders.Items.Add(ds.Tables(0).Rows(0).Item(0))                tempListViewItem.SubItems.Add(ds.Tables(0).Rows(0).Item(1))                Else                tempListViewItem = listviewOrders.Items.Add("")                tempListViewItem.SubItems.Add("")                End If             tempListViewItem.SubItems.Add(tempObjOrderInformation.quantity)             tempListViewItem.SubItems.Add(tempObjOrderInformation.quantity *             Double.Parse(ds.Tables(0).Rows(0).Item(1)))             dblTotalAmount = dblTotalAmount + tempObjOrderInformation.quantity *             Double.Parse(ds.Tables(0).Rows(0).Item(1))             Next             txtSubTotal.Text = dblTotalAmount             txtTotal.Text = dblTotalAmount          End If          Catch ex As Exception          MsgBox("Unable to retrieve order information.", MsgBoxStyle.OKOnly, "Retrieval Error")          Me.Close()       End Try    End Sub       Private Sub txtSubTotal_KeyPress(ByVal sender As Object, ByVal e As _       System.Windows.Forms.KeyPressEventArgs) Handles txtSubTotal.KeyPress       e.Handled = True    End Sub       Private Sub txtTotal_KeyPress(ByVal sender As Object, ByVal e As _       System.Windows.Forms.KeyPressEventArgs) Handles txtTotal.KeyPress       e.Handled = True    End Sub       Private Sub txtshipping_KeyPress(ByVal sender As Object, ByVal e As _       System.Windows.Forms.KeyPressEventArgs) Handles txtshipping.KeyPress       If Not Char.IsDigit(e.KeyChar) Then          If e.KeyChar = vbBack Then          Exit Sub          End If          e.Handled = True       End If    End Sub       Private Sub txtshipping_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)       Handles txtshipping.TextChanged       If txtshipping.Text = "" Then          txtshipping.Text = "0"       End If       txtTotal.Text = Double.Parse(txtSubTotal.Text) + Double.Parse(txtshipping.Text)    End Sub       Private Sub txtCreditCardNumber_KeyPress(ByVal sender As Object, ByVal e As _       System.Windows.Forms.KeyPressEventArgs) Handles txtCreditCardNumber.KeyPress       If Not Char.IsDigit(e.KeyChar) Then          If e.KeyChar = vbBack Then             Exit Sub          End If          e.Handled = True       End If    End Sub       Private Sub cashRadioButton_CheckedChanged(ByVal sender As System.Object, ByVal e As _       System.EventArgs) Handles cashRadioButton.CheckedChanged       If cashRadioButton.Checked = True Then          creditCardGroupBox.Enabled = False          Else          creditCardGroupBox.Enabled = True       End If    End Sub       Private Sub creditRadioButton_CheckedChanged(ByVal sender As System.Object, ByVal e As _       System.EventArgs) Handles creditRadioButton.CheckedChanged       If creditRadioButton.Checked = True Then          creditCardGroupBox.Enabled = True          Else          creditCardGroupBox.Enabled = False       End If    End Sub       Private Sub cmdGenerate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _  Handles cmdGenerate.Click       Dim dt As System.DateTime       If creditRadioButton.Checked = True Then          If txtNameOnCard.Text = "" Then             MsgBox("Please specify Name as on the credit card.", MsgBoxStyle.OKOnly, "Please _             specify the information")             Exit Sub          End If          If txtCreditCardNumber.Text = "" Then             MsgBox("Please specify credit card number.", MsgBoxStyle.OKOnly, "Please specify the information")             Exit Sub          End If          If dt.Today > dtPicker.Value Then             MsgBox("Your credit card has expired.", MsgBoxStyle.OKOnly, "Please check the information")             Exit Sub          End If       End If       Try       If txtshipping.Text = "" Then          txtshipping.Text = "0"       End If       'Create an object of the type Invoices that represent as invoice       Dim objInvoices As New Invoices       objInvoices.invoiceDate = dt.Today       objInvoices.orderId = orderId       objInvoices.shipping_handlingCost = txtshipping.Text       objInvoices.subTotal = txtSubTotal.Text       objInvoices.totalAmount = txtTotal.Text       If creditRadioButton.Checked = True Then          objInvoices.paymentMode = "credit  card"          Else          objInvoices.paymentMode = "cash"       End If       'Call the generateInvoice method of the class Invoices to save the Invoice       objInvoices.generateInvoice()       If creditRadioButton.Checked = True Then          'Create an object of the type InvoiceCreditCardInfo          Dim objInvoiceCreditCardInfo As New InvoiceCreditCardInfo(invoiceId,          txtNameOnCard.Text, txtCreditCardNumber.Text)          'Call the saveCreditCardInfo method to save the credit card information          objInvoiceCreditCardInfo.saveCreditCardInfo()       End If       boolInvoiceGeneration = True       Me.Close()       Catch ex As Exception       MsgBox("Unable to generate the invoice.", MsgBoxStyle.OKOnly, "Database Error")       boolInvoiceGeneration = False       Me.Close()       End Try            End Sub End Class 

 

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The above listing defines the following methods:

• Invoice_Load() : Calls the retrieveInvoiceId() method of the Invoices class to retrieve the id of the last invoice generated. This method also calls the retriveCustomerInformation() method of the Customer class to retrieve the information of the customer who placed a particular order. Then this method calls the RetrieveOrderInfo() method of the OrderInformation class to display the product information in the listviewOrders list view control.

• cmdGenerate_Click() : Executes when the administrator specifies the shipping and handling cost, selects the payment mode, and clicks the Generate Invoice button to generate the invoice. This method calls the generateInvoice() method of the Invoice class that saves the invoice information in the Invoices table.

Figure 2-11 shows the output of Listing 2-15:

Figure 2-11: The Invoice Window

Creating the Customer Registration Window

The CustomerRegistration class defines the CustomerRegistration window. The CustomerRegistration class enables a prospective customer to specify the necessary information for registration.

Listing 2-16 shows the code for the frmCustomerRegistration.vb that defines the CustomerRegistration class:

Listing 2-16: The frmCustomerRegistration.vb File

 Public Class CustomerRegistration Inherits System.Windows.Forms.Form       Private Sub cmdAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _          Handles cmdAdd.Click          'Check for the completion of required information If txtUsername.Text = "" _          ThenMsgBox("Please specify user name.", MsgBoxStyle.OKOnly, "Please check the           information")       Exit Sub       End If       If txtPassword.Text = "" Then          MsgBox("Please specify the password.", MsgBoxStyle.OKOnly, "Please check the information")          Exit Sub       End If       If txtaddress1.Text = "" Then          MsgBox("Please specify address1.", MsgBoxStyle.OKOnly, "Please check the information")          Exit Sub       End If       If txtCity.Text = "" Then          MsgBox("Please specify city.", MsgBoxStyle.OKOnly, "Please check the information")          Exit Sub       End If       If txtCountry.Text = "" Then          MsgBox("Please specify country.", MsgBoxStyle.OKOnly, "Please check the information")          Exit Sub       End If       If txtZipcode.Text = "" Then          MsgBox("Please specify zip code.",  MsgBoxStyle.OKOnly, "Please check the information")          Exit Sub       End If       If txtfirstname.Text = "" Then          MsgBox("Please specify user name.", MsgBoxStyle.OKOnly, "Please check the information")          Exit Sub       End If       Try          'An object of the class Customers that represents a customer          Dim objCustomers As New Customers          objCustomers.address1 = txtaddress1.Text          objCustomers.address2 = txtAddress2.Text          objCustomers.city = txtCity.Text          objCustomers.country = txtCountry.Text          objCustomers.firstName = txtFirstName.Text          objCustomers.lastName = txtLastName.Text          objCustomers.password = txtPassword.Text          objCustomers.username = txtUsername.Text          objCustomers.zipCode = txtZipcode.Text          custId = objCustomers.addCustomerInformation          If custId = 0 Then             MsgBox("Unable to save the information.", MsgBoxStyle.OKOnly,             "Database Error")             Else             MsgBox("You are registered sucessfully.Your username is " & txtUsername.Text             & ".",             MsgBoxStyle.OKOnly, "SUCCESS")          End If          Me.Close()          Catch ex As Exception          MsgBox("Unable to save the information", MsgBoxStyle.OKOnly, "Database Error")          Me.Close()       End Try    End Sub    Private Sub txtZipcode_KeyPress(ByVal sender As Object, ByVal e As       System.Windows.Forms.KeyPressEventArgs) Handles txtZipcode.KeyPress       If Not Char.IsDigit(e.KeyChar) Then          If e.KeyChar = vbBack Then          Exit Sub          End If          e.Handled = True       End If    End Sub End Class 

 

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In the above listing, the cmdAdd_Click() method executes when a prospective customer specifies customer information and clicks the Save button to save the information and register. This method checks the validity of the information and calls the addCustomerInformation() method of the Customers class that inserts the customer information in the Customers table.

Figure 2-12 shows the output of Listing 2-16:

Figure 2-12: The Customer Registration Window