File-Based Applications

A computer database can be created using almost any application that can be used to store text. Because databases have become a valuable means of holding company information, specialized software products have been developed to make it possible to store large and complex pieces of information.

A file-based database (also called a flat file database) is an application that stores one or various lists of information in regular, traditional text-based files.

To create a file-based application, you can use a simple or complex text editor such as Notepad. The main action from you is to create the list(s) and save it(them) as text files using either the txt or any extension of your choice. After creating a list, when necessary, you can open it to access and optionally change the values. After making the changes, you can save the file. In the same way, you can print the values and do any type of file-related operation that you judge necessary.

One of the disadvantages of using a text editor to create a database is that, if you decide to distribute it, either your users should know as much as necessary about the file (its location and its content, just to name a few) you must provide a mechanical means of accessing the file(s). To make your product more professional and user friendly, you can create a graphical application that the user would use to access the values in the database. With this approach, you can create an attractive graphical user interface (GUI) object that display a functionality the user is familiar with. Using such an aesthetic interface, you can provide the means of adding, editing, deleting, or changing the values of the database.

To create a file-based application, you can use the Microsoft Visual Basic programming environment that, in combination with the .NET Framework, provides all the tools you would need.

To create an aesthetically user-friendly application, you can use the various Windows controls that are implemented in the .NET Framework. The controls are varied and are meant to accomplish different roles:

• The form is the most fundamental control. As a container, in fact the main container, it is the primary object that holds the other controls of an application
• Based on its fundamental role in an application, a form can be equipped with functional accessories placed on its frame and intended to assist with file or print operations. These accessories are the menu(s), the toolbar(s), and the status bar
• A dialog box is a special type of form you create to perform the same actions as a form but it does not use the accessories and it may show a different type of border
• On top of the form or the dialog box, there are controls, referred to as containers, that can be used to carry or hold other controls. These are the property sheet, the group box, or the panel
• Text-based controls are used to receive or display text. These are the label, the text box, the masked text box, and the link label
• Some text-based controls can display enhanced or formatted text beyond the functionality of the traditional text box. Besides the formatting and the characteristics of their paragraph, they may also display pictures. These controls are the rich text box and the web browser
• Button-based controls allow the user to perform an action when clicked. These controls are the command button, the radio button, and the check box
• List-based controls display a list of items to the user. This type includes the list box, the combo box, the tree view, the list view, and the domain up/down
• Date and time-based controls are specialized to handle date and time values. The controls in this category are the calendar and the date/time picker
• There are other controls used to show a value (the numeric up-down control) or a progress (the progress bar), etc

1. Start Microsoft Visual Basic and create a Windows Forms Application named GeorgetownDryCleaner1
2. In the Solution Explorer, right-click Form1.vb and click Rename
3. Type Central.vb and press Enter
4. From the Menus & Toolbars section of the Toolbox, click MenuStrip and click the form
5. While the menu strip is still selected, in the Properties window, click (Name) and type mnuMain
6. Under the Properties window, click Insert Standard Items
7. On the form, click Help and press Delete
8. Click Tools and press Delete
9. Click Edit and press Delete
10. Click File, click Save As and press Delete
11. Using the Properties window, change the names of the menu items as follows:
     

    Text	New Name
    &File	mnuFile
    &New	mnuFileNew
    &Open	mnuFileOpen
    &Save	mnuFileSave
    &Print	mnuFilePrint
    Print Pre&view	mnuFilePrintPreview

12. Design the form as follows:
     

    Control Name Text Additional Properties GroupBox   Order Identification   Label   &Receipt #:   TextBox txtReceiptNumber 1000 TextAlign: Right Label   Customer Name:   TextBox txtCustomerName     Label   Customer Phone:   TextBox txtCustomerPhone     Label   Date Left:   DateTimePicker dtpDateLeft     Label   Time Left:   DateTimePicker dtpTimeLeft   Format: Time Label   Date Expected:   DateTimePicker dtpDateExpected     Label   Time Expected:   DateTimePicker dtpTimeExpected   Format: Time Label   Order &Status:   ComboBox cbxOrderStatus     Label   D&ate Picked Up:   DateTimePicker dtpDatePickedUp     Label   Time Pic&kep Up:   DateTimePicker dtpTimePickedUp     GroupBox   Order Processing   Label   Item Type   Label   Unit Price   Label   Qty   Label   Sub Total   Label   Shirts   TextBox txtShirtsUnitPrice 1.25 TextAlign: Right TextBox txtShirtsQuantity 0 TextAlign: Right TextBox txtShirtsSubTotal 0.00 TextAlign: Right Label   Pants   TextBox txtPantsUnitPrice 1.95 TextAlign: Right TextBox txtPantsQuantity   TextAlign: Right TextBox txtPantsSubTotal 0.00 TextAlign: Right ComboBox cbxItem1 None Items: None Women Suit Dress Regular Skirt Skirt With Hook Men's Suit 2Pc Men's Suit 3Pc Sweaters Silk Shirt Tie Coat Jacket Swede TextBox txtItem1UnitPrice 0.00 TextAlign: Right TextBox txtItem1Quantity 0 TextAlign: Right TextBox txtItem1SubTotal 0.00 TextAlign: Right ComboBox cbxItem2 None Items: None Women Suit Dress Regular Skirt Skirt With Hook Men's Suit 2Pc Men's Suit 3Pc Sweaters Silk Shirt Tie Coat Jacket Swede TextBox txtItem2UnitPrice 0.00 TextAlign: Right TextBox txtItem2Quantity 0 TextAlign: Right TextBox txtItem2SubTotal 0.00 TextAlign: Right ComboBox cbxItem3 None Items: None Women Suit Dress Regular Skirt Skirt With Hook Men's Suit 2Pc Men's Suit 3Pc Sweaters Silk Shirt Tie Coat Jacket Swede TextBox txtItem3UnitPrice 0.00 TextAlign: Right TextBox txtItem3Quantity 0 TextAlign: Right TextBox txtItem3SubTotal 0.00 TextAlign: Right ComboBox cbxItem4 None Items: None Women Suit Dress Regular Skirt Skirt With Hook Men's Suit 2Pc Men's Suit 3Pc Sweaters Silk Shirt Tie Coat Jacket Swede TextBox txtItem4UnitPrice 0.00 TextAlign: Right TextBox txtItem4Quantity 0 TextAlign: Right TextBox txtItem4SubTotal 0.00 TextAlign: Right GroupBox   Order Summary   Label   Cleaning Total:   TextBox txtCleaningTotal 0.00 TextAlign: Right Label   Tax Rate:   TextBox txtTaxRate 7.75 TextAlign: Right Label   %   Label   Tax Amount:   TextBox txtTaxAmount 0.00 TextAlign: Right Label   Net Total:   TextBox txtNetPrice 0.00 TextAlign: Right

13. Double-click the Time Left control and implement its ValueChanged event as follows:
     

    Private Sub dtpTimeLeft_ValueChanged(ByVal sender As System.Object, _ ByVal e As System.EventArgs) _ Handles dtpTimeLeft.ValueChanged Dim DateLeft As Date = dtpDateLeft.Value Dim TimeLeft As Date = dtpTimeLeft.Value Dim Time9AM As Date = New DateTime(TimeLeft.Year, _ TimeLeft.Month, _ TimeLeft.Day, 9, 0, 0) ' If the customer leaves clothes before 9AM... If TimeLeft <= Time9AM Then ' ... then they should be ready the same day after 5PM dtpDateExpected.Value = DateLeft dtpTimeExpected.Value = New DateTime(DateLeft.Year, _ DateLeft.Month, _ DateLeft.Day, 17, 0, 0) Else ' If the clothes were left after 9AM, ' then they will be available the following business morning at 8AM ' If the following day is Sunday, ' then they will be ready the following Monday If DateLeft.DayOfWeek = DayOfWeek.Saturday Then dtpDateExpected.Value = DateLeft.AddDays(2D) dtpTimeExpected.Value = New DateTime(DateLeft.Year, _ DateLeft.Month, _ DateLeft.Day + 2, 8, 0, 0) Else dtpDateExpected.Value = New DateTime(DateLeft.Year, _ DateLeft.Month, _ DateLeft.Day + 1) dtpTimeExpected.Value = New DateTime(DateLeft.Year, _ DateLeft.Month, _ DateLeft.Day + 1, 8, 0, 0) End If End If End Sub

14. Return to the form

One of the biggest differences between a database and a regular application is that, traditionally, although not always, all of the files of a database are located in the same directory. The directory can be local and accessed only by one computer. The directory can be located in one computer and accessed by various users on different computers or a workgroup. The directory can be located on a server that no user directly uses but that directory's files can be accessed from one or more computers.

Another particularity of a database is that usually you, the database developer, create and manage the directory or directories used by the application.

Another difference of a database as compared to a regular application is that, while using the database, users do not create files. This means that there is no actual file processing on the part of the users. For example, the user does not even open the database in the traditional sense. You, the database developer, provides a means of accessing the database. Then, the user adds, edits, or deletes values.

Based on the above discussion of directories, when creating a file-based application, one the first actions you should perform consists of setting up the directory where the file(s) of your application would be located. If you already know (and you should know) where and how the application would be accessed, you can manually create a folder using Windows Explorer, My Computer, or any appropriate utility. Otherwise, you can still programmatically create the directory.

The .NET Framework supports the creation and management of directories through various classes. The main class used to deal with directories is called Directory. Besides the Directory class, the .NET Framework provides support for folders through a class named DirectoryInfo. To use it, declare a variable of type DirectoryInfo using its constructor to initialize it.

To actually create a directory using the static Directory class, you can call its CreateDirectory() method that is overloaded with two versions. Here is an example:

Imports System.IO

Public Class Exercise

    Private Sub btnDirectory_Click(ByVal sender As System.Object, _
                                   ByVal e As System.EventArgs) _
                                   Handles btnDirectory.Click
        Directory.CreateDirectory("E:\Bethesda Car Rental")
    End Sub
End Class

To create a folder using the DirectoryInfo class, call its Create() method that comes in two versions. Here is an example:

Private Sub btnDirectory_Click(ByVal sender As System.Object, _
                                   ByVal e As System.EventArgs) _
                                   Handles btnDirectory.Click
    Dim Folder As DirectoryInfo = New DirectoryInfo("E:\Bethesda Car Rental")
    Folder.Create()
End Sub

When you call either the Directory.CreateDirectory() method or the DirectoryInfo.Create() method, if the directory does not exist, it would be created. If the directory exists already, nothing would happen. This implies that the compiler would not attempt to create a directory if there is already one in the indicated location and you can safely call any of these methods without the risk of deleting its existing files, if any.

Before performing any operation on a directory, you should first make sure it exists. To get this information, you can call the Directory.Exists() method that returns a Boolean value. This method takes as argument the path to the directory. Here is an example:

Private Sub btnDirectory_Click(ByVal sender As System.Object, _
                                   ByVal e As System.EventArgs) _
                                   Handles btnDirectory.Click
        If Directory.Exists("E:\Bethesda Car Rental") Then
            MsgBox("The directory exists already")
        Else
            MsgBox("That directory was not yet created")
        End If
End Sub

During the lifetime of your database, at one time, you may want to change its location, for any reason you judge necessary. Although this operation is primarily easily supported, it could become complex in some scenarios. Still, to move a directory and its contents, you can call the Directory.Move() method. This method takes two arguments: the source and the destination. After the method has been called, the directory held by the first argument would be moved, along with its sub-folders and files, to the path specified by the second argument. To move a directory using the DirectoryInfo class, you can call its MoveTo() method.

As opposed to creating a directory, if you do not need it anymore, you can remove it. To support this, the Directory class is equipped with the Delete() method that is overloaded with two versions. One of the versions is used to delete a directory that is currently empty while the other version is used to delete the directory and its content.

1. In the top section of the file, type Imports System.IO and press Enter to have it on its own line
2. Under the Class Central line, declare three variables as follows:
    

   Imports System.IO Public Class Central Private iFilename As Integer Private IsNewCleaningOrder As Boolean Private Filename As String

3. In the Class Name combo box, select mnuFileNew
4. In the Method Name combo box, select Click and implement the event as follows:
    

   Private Sub mnuFileNew_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) _ Handles mnuFileNew.Click ' We will store our files in the following folder Dim FolderName As String = "C:\Georgetown Dry Cleaner\Receipts" Dim Folder = Directory.CreateDirectory(FolderName) ' Get the list of files, if any, from our directory Dim ListOfFiles() = Folder.GetFiles() ' If there is no file in the directory, ' then we will use 1000 as the first file name If ListOfFiles.Length = 0 Then iFilename = 1000 Else ' If there was at least one file in the directory ' Get a reference to the last file Dim LastFile As FileInfo = ListOfFiles(ListOfFiles.Length - 1) ' Get the name of the last file without its extension Dim fwe As String = Path.GetFileNameWithoutExtension(LastFile.FullName) ' Increment the name of the file by 1 Try iFilename = CInt(fwe) + 1 Catch Exc As FormatException End Try End If ' Update our global name of the file Filename = FolderName & "\" & CStr(iFilename)& ".gcs" txtReceiptNumber.Text = iFilename.ToString() txtCustomerName.Text = "" txtCustomerPhone.Text = "" dtpDateLeft.Value = DateTime.Today dtpTimeLeft.Value = DateTime.Today dtpDateExpected.Value = DateTime.Today dtpTimeExpected.Value = DateTime.Today cbxStatus.Text = "Not Yet Ready" dtpDatePickedUp.Value = DateTime.Today dtpTimePickedUp.Value = DateTime.Today txtUnitPriceShirts.Text = "1.25" txtQuantityShirts.Text = "0" txtSubTotalShirts.Text = "0.00" txtUnitPricePants.Text = "1.95" txtQuantityPants.Text = "0" txtSubTotalPants.Text = "0.00" cbxItem1.Text = "None" txtUnitPriceItem1.Text = "0.00" txtQuantityItem1.Text = "0" txtSubTotalItem1.Text = "0.00" cbxItem2.Text = "None" txtUnitPriceItem2.Text = "0.00" txtQuantityItem2.Text = "0" txtSubTotalItem2.Text = "0.00" cbxItem3.Text = "None" txtUnitPriceItem3.Text = "0.00" txtQuantityItem3.Text = "0" txtSubTotalItem3.Text = "0.00" cbxItem4.Text = "None" txtUnitPriceItem4.Text = "0.00" txtQuantityItem4.Text = "0" txtSubTotalItem4.Text = "0.00" txtCleaningTotal.Text = "0.00" txtTaxRate.Text = "7.75" txtTaxAmount.Text = "0.00" txtCleaningTotal.Text = "0.00" txtCustomerName.Focus() End Sub

5. Return to the form

As its name indicates, a file-base application uses one or more files to hold its information. If you decide to create the application using the Visual Basic language, you can take advantage of the .NET Framework rich library and its support for file processing.

In the .NET Framework, file processing is primarily supported through the System.IO namespace that is filled with various classes to deal with files and directories (folders). The most fundamental class of the System.IO namespace and used to perform file processing is called File. The abstract and sealed File class contains all necessary methods used to create a file, check the existence of a file, write information to a file, read information from a file, or manipulate the system attributes of a file.

Another one of the fundamental file processing classes is called Stream. This is mainly an abstract class that lays a foundation for other stream-oriented classes. One of the classes that derives from Stream is called FileStream.

To create a new file, you can use the File class, call one of the versions of its Create() method that takes an argument as the name of, or the path to, the file and returns a FileStream object.

Besides File, you can use the StreamWriter class to create a file. To do this, declare a variable of type StreamWriter and initialize it using one of its constructors.

One of the most routine operations performed on a class consists of writing information to it. And one of the most useful classes in this domain is called StreamWriter. The StreamWriter class is derived from the TextWriter class. To create a file using the StreamWriter class, you can declare a StreamWriter variable and initialize it using one of its constructors. After creating the file, you can write information to it by calling the Write() or the WriteLine() method. Always make sure you close the stream after using it. Also make sure you use exception handling in your code.

Here is an example:

Imports System.IO

Public Class Exercise

    
    Private Sub txtLastName_Leave(ByVal sender As System.Object, _
                                  ByVal e As System.EventArgs) _
                                  Handles txtLastName.Leave
        Dim strInitials As String = txtFirstName.Text.Substring(0, 1) & _
                                    txtLastName.Text.Substring(0, 1)
        txtSave.Text = strInitials
    End Sub

    Private Sub btnSave_Click(ByVal sender As Object, _
                              ByVal e As System.EventArgs) _
                              Handles btnSave.Click
        Dim stmWrite As StreamWriter = New StreamWriter(txtSave.Text)

        stmWrite.WriteLine(txtFirstName.Text)
        stmWrite.WriteLine(txtLastName.Text)
        stmWrite.WriteLine(dtpDateHired.Value)
        stmWrite.WriteLine(cbxGenders.Text)
        stmWrite.WriteLine(txtHourlySalary.Text)

        stmWrite.Close()

        txtFirstName.Text = ""
        txtLastName.Text = ""
        dtpDateHired.Value = DateTime.Today
        cbxGenders.Text = "Unknown"
        txtHourlySalary.Text = "0.00"
        txtSave.Text = ""
        txtOpen.Text = ""
    End Sub
End Class

Besides StreamWriter, to create a file and write information to it, you can use the BinaryWriter class. You start by declaring a BinaryWriter variable and initialize it using one of its constructors, passing a Stream-based object.

1. Under the previous End Sub line, define a sub procedure as follows:
    

   Private Sub SaveCleaningOrder() ' We will store our files in the following folder Dim FolderName As String = "C:\Georgetown Dry Cleaner\Receipts" Dim Folder As DirectoryInfo = Directory.CreateDirectory(FolderName) ' Get the list of files, if any, from our directory Dim ListOfFiles() As FileInfo = Folder.GetFiles() ' If this is a new cleaning order, ' get ready to create a name for the file If IsNewCleaningOrder = True Then ' If there is no file in the directory, ' then we will use 1000 as the first file name If ListOfFiles.Length = 0 Then iFilename = 1000 Else ' If there was at least one file in the directory ' Get a reference to the last file Dim LastFile As FileInfo = ListOfFiles(ListOfFiles.Length - 1) ' Get the name of the last file without its extension Dim fwe As String = Path.GetFileNameWithoutExtension(LastFile.FullName) ' Increment the name of the file by 1 iFilename = CInt(fwe) + 1 End If ' Update our global name of the file Filename = FolderName & "\" & CStr(iFilename)& ".gcs" txtReceiptNumber.Text = iFilename.ToString() IsNewCleaningOrder = False ' If a cleaning order was already opened, we will simply update it Else Filename = "C:\Georgetown Dry Cleaner\Receipts\" & _ txtReceiptNumber.Text & ".gcs" End If Dim stmGCS As StreamWriter = New StreamWriter(Filename) Try stmGCS.WriteLine(txtCustomerName.Text) stmGCS.WriteLine(txtCustomerPhone.Text) stmGCS.WriteLine(dtpDateLeft.Value.ToString("D")) stmGCS.WriteLine(dtpTimeLeft.Value.ToString("t")) stmGCS.WriteLine(dtpDateExpected.Value.ToString("D")) stmGCS.WriteLine(dtpTimeExpected.Value.ToString("t")) stmGCS.WriteLine(cbxStatus.Text) stmGCS.WriteLine(dtpDatePickedUp.Value.ToString("D")) stmGCS.WriteLine(dtpTimePickedUp.Value.ToString("t")) stmGCS.WriteLine(txtUnitPriceShirts.Text) stmGCS.WriteLine(txtQuantityShirts.Text) stmGCS.WriteLine(txtSubTotalShirts.Text) stmGCS.WriteLine(txtUnitPricePants.Text) stmGCS.WriteLine(txtQuantityPants.Text) stmGCS.WriteLine(txtSubTotalPants.Text) stmGCS.WriteLine(cbxItem1.Text) stmGCS.WriteLine(txtUnitPriceItem1.Text) stmGCS.WriteLine(txtQuantityItem1.Text) stmGCS.WriteLine(txtSubTotalItem1.Text) stmGCS.WriteLine(cbxItem2.Text) stmGCS.WriteLine(txtUnitPriceItem2.Text) stmGCS.WriteLine(txtQuantityItem2.Text) stmGCS.WriteLine(txtSubTotalItem2.Text) stmGCS.WriteLine(cbxItem3.Text) stmGCS.WriteLine(txtUnitPriceItem3.Text) stmGCS.WriteLine(txtQuantityItem3.Text) stmGCS.WriteLine(txtSubTotalItem3.Text) stmGCS.WriteLine(cbxItem4.Text) stmGCS.WriteLine(txtUnitPriceItem4.Text) stmGCS.WriteLine(txtQuantityItem4.Text) stmGCS.WriteLine(txtSubTotalItem4.Text) stmGCS.WriteLine(txtCleaningTotal.Text) stmGCS.WriteLine(txtTaxRate.Text) stmGCS.WriteLine(txtTaxAmount.Text) stmGCS.WriteLine(txtNetPrice.Text) Finally stmGCS.Close() End Try End Sub

2. Under the above End Sub line, implement an event as follows:
    

   Private Sub ControlLeave(ByVal Sender As Object, ByVal e As EventArgs) _ Handles txtUnitPriceShirts.Leave, _ txtUnitPricePants.Leave, _ txtUnitPriceItem1.Leave, _ txtUnitPriceItem2.Leave, _ txtUnitPriceItem3.Leave, _ txtUnitPriceItem4.Leave, _ txtQuantityShirts.Leave, _ txtQuantityPants.Leave, _ txtQuantityItem1.Leave, _ txtQuantityItem2.Leave, _ txtQuantityItem3.Leave, _ txtQuantityItem4.Leave, _ txtTaxRate.Leave Dim UnitPriceShirts As Double Dim UnitPricePants As Double Dim UnitPriceItem1 As Double Dim UnitPriceItem2 As Double Dim UnitPriceItem3 As Double Dim UnitPriceItem4 As Double Dim SubTotalShirts As Double Dim SubTotalPants As Double Dim SubTotalItem1 As Double Dim SubTotalItem2 As Double Dim SubTotalItem3 As Double Dim SubTotalItem4 As Double Dim QuantityShirts As Integer = 1 Dim QuantityPants As Integer = 1 Dim QuantityItem1 As Integer = 1 Dim QuantityItem2 As Integer = 1 Dim QuantityItem3 As Integer = 1 Dim QuantityItem4 As Integer = 4 Dim CleaningTotal As Double Dim TaxRate As Double Dim TaxAmount As Double Dim NetPrice As Double ' Retrieve the unit price of this item ' Just in case the user types an invalid value, ' we are using a try...catch Try unitPriceShirts = CDbl(txtUnitPriceShirts.Text) Catch Exc As FormatException MsgBox("The value you entered for the price of " & _ "shirts is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try ' Retrieve the number of this item ' Just in case the user types an invalid value, ' we are using a try...catch Try QuantityShirts = CInt(txtQuantityShirts.Text) Catch Exc As FormatException MsgBox("The value you entered for the number of " & _ "shirts is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try Try UnitPricePants = CDbl(txtUnitPricePants.Text) Catch Exc As FormatException MsgBox("The value you entered for the price of " & _ "pants is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try Try QuantityPants = CInt(txtQuantityPants.Text) Catch Exc As FormatException MsgBox("The value you entered for the number of " & _ "pants is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try If (cbxItem1.Text = "None") Or (cbxItem1.Text = "") Then QuantityItem1 = 0 UnitPriceItem1 = 0.0 Else Try UnitPriceItem1 = CDbl(txtUnitPriceItem1.Text) Catch Exc As FormatException MsgBox("The value you entered for the price is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try Try QuantityItem1 = CInt(txtQuantityItem1.Text) Catch Exc As FormatException MsgBox("The value you entered is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try End If If (cbxItem2.Text = "None") Or (cbxItem2.Text = "") Then QuantityItem2 = 0 UnitPriceItem2 = 0.0 Else Try UnitPriceItem2 = CDbl(txtUnitPriceItem2.Text) Catch Exc As FormatException MsgBox("The value you entered for " & _ "the price is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try Try QuantityItem2 = CInt(txtQuantityItem2.Text) Catch Exc As FormatException MsgBox("The value you entered is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try End If If (cbxItem3.Text = "None") Or (cbxItem3.Text = "") Then QuantityItem3 = 0 UnitPriceItem3 = 0.0 Else Try UnitPriceItem3 = CDbl(txtUnitPriceItem3.Text) Catch Exc As FormatException MsgBox("The value you entered for the " & _ "price is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try Try QuantityItem3 = CInt(txtQuantityItem3.Text) Catch Exc As FormatException MsgBox("The value you entered is not valid" & _ vbCrLf & "Please try again") Exit Sub End Try End If If (cbxItem4.Text = "None") Or (cbxItem4.Text = "") Then QuantityItem4 = 0 UnitPriceItem4 = 0.0 Else Try UnitPriceItem4 = CDbl(txtUnitPriceItem4.Text) Catch Exc As FormatException MsgBox("The value you entered for the price is not valid" & _ vbcrlf & "Please try again") Exit Sub End Try Try QuantityItem4 = CInt(txtQuantityItem4.Text) Catch Exc As FormatException MsgBox("The value you entered is not valid" & _ vbcrlf & "Please try again") Exit Sub End Try End If ' Calculate the sub-total for this item SubTotalShirts = QuantityShirts * unitPriceShirts SubTotalPants = QuantityPants * UnitPricePants SubTotalItem1 = QuantityItem1 * UnitPriceItem1 SubTotalItem2 = QuantityItem2 * UnitPriceItem2 SubTotalItem3 = QuantityItem3 * UnitPriceItem3 SubTotalItem4 = QuantityItem4 * UnitPriceItem4 ' Calculate the total based on sub-totals CleaningTotal = SubTotalShirts + SubTotalPants + SubTotalItem1 + _ SubTotalItem2 + SubTotalItem3 + SubTotalItem4 TaxRate = CDbl(txtTaxRate.Text) ' Calculate the amount owed for the taxes TaxAmount = cleaningTotal * TaxRate / 100 ' Add the tax amount to the total order NetPrice = cleaningTotal + TaxAmount ' Display the sub-total in the corresponding text box txtSubTotalShirts.Text = FormatNumber(SubTotalShirts) txtSubTotalPants.Text = FormatNumber(SubTotalPants) txtSubTotalItem1.Text = FormatNumber(SubTotalItem1) txtSubTotalItem2.Text = FormatNumber(SubTotalItem2) txtSubTotalItem3.Text = FormatNumber(SubTotalItem3) txtSubTotalItem4.Text = FormatNumber(SubTotalItem4) txtCleaningTotal.Text = FormatNumber(CleaningTotal) txtTaxAmount.Text = FormatNumber(TaxAmount) txtNetPrice.Text = FormatNumber(NetPrice) SaveCleaningOrder() End Sub

3. In the Class Name combo box, select mnuFileSave
4. In the Method Name combo box, select Click and implement the event as follows:
    

   Private Sub mnuFileSave_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) _ Handles mnuFileSave.Click SaveCleaningOrder() End Sub

5. Execute the application
6. Create a cleaning order
    
   
7. Click New and create a few more cleaning orders
    
   
8. Close the form and return to your programming environment

Before exploring the contents of a file, you must first open. To open a file using the File class, you can call its Open method that is overloaded with three versions. If the information in the file is raw text, you can call the OpenText() method. After opening a file, you can read its content.

To support the ability to read from a file, you can use the StreamReader class. The StreamReader class is derived from the TextReader class. When using it, you can start by opening the file. To do this, declare a variable of type StreamReader and use one of its constructor to specify the name of, or the path to, the file. To read information from the file, you can call its Read() or its ReadLine() method. Here is an example:

Private Sub btnOpen_Click(ByVal sender As Object, _
                              ByVal e As System.EventArgs) _
                              Handles btnOpen.Click
        Dim stmReader As StreamReader = New StreamReader(txtOpen.Text)

        txtFirstName.Text = stmReader.ReadLine()
        txtLastName.Text = stmReader.ReadLine()
        dtpDateHired.Value = DateTime.Parse(stmReader.ReadLine())
        cbxGenders.Text = stmReader.ReadLine()
        txtHourlySalary.Text = stmReader.ReadLine()

        stmReader.Close()
End Sub

Instead of StreamReader, you can use the BinaryReader class to read information from a file.

1. In the Class Name combo box, select mnuFileOpen
2. In the Method Name combo box, select Click and implement the event as follows:
    

   Private Sub mnuFileOpen_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) _ Handles mnuFileOpen.Click If txtReceiptNumber.Text = "" Then Exit Sub Else Try IsNewCleaningOrder = False Filename = "C:\Georgetown Dry Cleaner\Receipts\" & _ txtReceiptNumber.Text & ".gcs" Dim rdrGCS As StreamReader = New StreamReader(Filename) Try txtCustomerName.Text = rdrGCS.ReadLine() txtCustomerPhone.Text = rdrGCS.ReadLine() dtpDateLeft.Value = DateTime.Parse(rdrGCS.ReadLine()) dtpTimeLeft.Value = DateTime.Parse(rdrGCS.ReadLine()) dtpDateExpected.Value = DateTime.Parse(rdrGCS.ReadLine()) dtpTimeExpected.Value = DateTime.Parse(rdrGCS.ReadLine()) cbxStatus.Text = rdrGCS.ReadLine() dtpDatePickedUp.Value = DateTime.Parse(rdrGCS.ReadLine()) dtpTimePickedUp.Value = DateTime.Parse(rdrGCS.ReadLine()) txtUnitPriceShirts.Text = rdrGCS.ReadLine() txtQuantityShirts.Text = rdrGCS.ReadLine() txtSubTotalShirts.Text = rdrGCS.ReadLine() txtUnitPricePants.Text = rdrGCS.ReadLine() txtQuantityPants.Text = rdrGCS.ReadLine() txtSubTotalPants.Text = rdrGCS.ReadLine() cbxItem1.Text = rdrGCS.ReadLine() txtUnitPriceItem1.Text = rdrGCS.ReadLine() txtQuantityItem1.Text = rdrGCS.ReadLine() txtSubTotalItem1.Text = rdrGCS.ReadLine() cbxItem2.Text = rdrGCS.ReadLine() txtUnitPriceItem2.Text = rdrGCS.ReadLine() txtQuantityItem2.Text = rdrGCS.ReadLine() txtSubTotalItem2.Text = rdrGCS.ReadLine() cbxItem3.Text = rdrGCS.ReadLine() txtUnitPriceItem3.Text = rdrGCS.ReadLine() txtQuantityItem3.Text = rdrGCS.ReadLine() txtSubTotalItem3.Text = rdrGCS.ReadLine() cbxItem4.Text = rdrGCS.ReadLine() txtUnitPriceItem4.Text = rdrGCS.ReadLine() txtQuantityItem4.Text = rdrGCS.ReadLine() txtSubTotalItem4.Text = rdrGCS.ReadLine() txtCleaningTotal.Text = rdrGCS.ReadLine() txtTaxRate.Text = rdrGCS.ReadLine() txtTaxAmount.Text = rdrGCS.ReadLine() txtNetPrice.Text = rdrGCS.ReadLine() Finally rdrGCS.Close() End Try Catch Exc As FileNotFoundException MsgBox("There is no cleaning order with that receipt number") End Try End If End Sub

3. Execute the application
4. Type 1001 for the receipt number and, on the main menu of the form, click File -> Open
5. Close the form and return to your programming environment

We have mentioned that, on a typical database, the user is not aware of opening or saving files. In the same way, the user can be spared with deciding when to save and when not to save data. Whenever possible, most operations should be performed behind-the-scenes with little to no intervention from the user. To make this possible, you are in charge of creating the file(s), receiving data from the user, and then adding that data to the file.

1. In the Class Name combo box, select (Central Events)
2. In the Method Name combo box, select Load and implement the event as follows:
    

   Private Sub Central_Load(ByVal sender As Object, _ ByVal e As System.EventArgs) _ Handles Me.Load mnuFileNew_Click(sender, e) End Sub

3. Save all

Data input, also referred to as data entry, consists of entering the values into the application. The user does it mainly using the keyboard and the mouse. As we reviewed the Windows controls, there are various types of objects you can use to assist the user. One of the suggestions you should follow is that you should make the user's job as easy as you can. Because users of a database are not expected to do any heavy word processing. This means that typing speed is not among their strongest points. Instead, when choosing the Windows controls for your application, you should select the most appropriate one for a particular piece of information.

Data output consists of retrieving information from a database. Besides opening the objects, such as the forms, that hold the information of a database, users also regular want to print. In fact, in some businesses, the customers require to have a printed copy of their transaction. Therefore, if you are in the habit of neglecting to configuring printing in your Windows applications, for a database, you should (strongly) loose the habit and provide your users with the ability to print the data of your application.

If you are creating a file-based application, you can use the various printing classes of the .NET Framework. Unfortunately, there is no environment inside the Microsoft Visual Studio 2005 that can assist you to visually design a report. You must manually draw everything.

1. From the Printing section of the Toolbox, click PrintDocument and click the form
2. While the new control is still selected, in the Properties window, click the Properties button, click (Name), type docPrint and press Enter
3. Under the form, double-click docPrint and implement its event as follows:
    

   Private Sub docPrint_PrintPage(ByVal sender As Object, _ ByVal e As System.Drawing.Printing.PrintPageEventArgs) _ Handles docPrint.PrintPage e.Graphics.DrawLine(New Pen(Color.Black, 2), 60, 90, 720, 90) e.Graphics.DrawLine(New Pen(Color.Black, 1), 60, 93, 720, 93) Dim strDisplay As String = "Georgetown Dry Cleaning Services" Dim fntString As System.Drawing.Font = New Font("Times New Roman", _ 28, FontStyle.Bold) e.Graphics.DrawString(strDisplay, fntString, _ Brushes.Black, 80, 100) strDisplay = "Customer Cleaning Order" fntString = New System.Drawing.Font("Times New Roman", 18, _ FontStyle.Bold) e.Graphics.DrawString(strDisplay, fntString, _ Brushes.Black, 220, 150) e.Graphics.DrawLine(New Pen(Color.Black, 1), 60, 184, 720, 184) e.Graphics.DrawLine(New Pen(Color.Black, 2), 60, 188, 720, 188) fntString = New System.Drawing.Font("Times New Roman", 12, _ FontStyle.Bold) e.Graphics.DrawString("", fntString, _ Brushes.Black, 80, 200) fntString = New System.Drawing.Font("Times New Roman", 12, _ FontStyle.Bold) e.Graphics.DrawString("Customer Identification: ", fntString, _ Brushes.Black, 100, 220) fntString = New System.Drawing.Font("Times New Roman", 12, _ FontStyle.Regular) e.Graphics.DrawString(txtCustomerName.Text & " - " & _ txtCustomerPhone.Text, fntString, _ Brushes.Black, 300, 220) e.Graphics.DrawLine(New Pen(Color.Black, 1), 100, 240, 700, 240) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString("Date Left: ", fntString, _ Brushes.Black, 100, 260) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(dtpDateLeft.Value.ToString("D"), fntString, _ Brushes.Black, 300, 260) e.Graphics.DrawLine(New Pen(Color.Black, 1), 100, 280, 700, 280) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString("Time Left: ", fntString, _ Brushes.Black, 500, 260) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(dtpTimeLeft.Value.ToString("t"), fntString, _ Brushes.Black, 620, 260) fntString = New System.Drawing.Font("Times New Roman", _ 12, FontStyle.Bold) e.Graphics.DrawString("Date Expected: ", fntString, _ Brushes.Black, 100, 300) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(dtpDateExpected.Value.ToString("D"), _ fntString, Brushes.Black, 300, 300) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString("Time Expected: ", fntString, _ Brushes.Black, 500, 300) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(dtpTimeExpected.Value.ToString("t"), _ fntString, Brushes.Black, 620, 300) e.Graphics.DrawLine(New Pen(Color.Black, 2), 100, 320, 700, 320) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString("Item Type", _ fntString, Brushes.Black, 140, 350) e.Graphics.DrawString("Unit Price", _ fntString, Brushes.Black, 300, 350) e.Graphics.DrawString("Quantity", _ fntString, Brushes.Black, 405, 350) e.Graphics.DrawString("Sub-Total", _ fntString, Brushes.Black, 500, 350) e.Graphics.DrawLine(New Pen(Color.Black, 2), 140, 370, 640, 370) Dim fmtString As StringFormat = New StringFormat fmtString.Alignment = StringAlignment.Far e.Graphics.DrawString("Shirts", _ fntString, Brushes.Black, 150, 380) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(txtUnitPriceShirts.Text, fntString, _ Brushes.Black, 350, 380, fmtString) e.Graphics.DrawString(txtQuantityShirts.Text, fntString, _ Brushes.Black, 440, 380, fmtString) e.Graphics.DrawString(txtSubTotalShirts.Text, fntString, _ Brushes.Black, 550, 380, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 1), 140, 400, 640, 400) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString("Pants", _ fntString, Brushes.Black, 150, 410) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(txtUnitPricePants.Text, fntString, _ Brushes.Black, 350, 410, fmtString) e.Graphics.DrawString(txtQuantityPants.Text, fntString, _ Brushes.Black, 440, 410, fmtString) e.Graphics.DrawString(txtSubTotalPants.Text, fntString, _ Brushes.Black, 550, 410, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 1), 140, 430, 640, 430) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString(cbxItem1.Text, _ fntString, Brushes.Black, 150, 440) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(txtUnitPriceItem1.Text, fntString, _ Brushes.Black, 350, 440, fmtString) e.Graphics.DrawString(txtQuantityItem1.Text, fntString, _ Brushes.Black, 440, 440, fmtString) e.Graphics.DrawString(txtSubTotalItem1.Text, fntString, _ Brushes.Black, 550, 440, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 1), 140, 460, 640, 460) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString(cbxItem2.Text, _ fntString, Brushes.Black, 150, 470) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(txtUnitPriceItem2.Text, fntString, _ Brushes.Black, 350, 470, fmtString) e.Graphics.DrawString(txtQuantityItem2.Text, fntString, _ Brushes.Black, 440, 470, fmtString) e.Graphics.DrawString(txtSubTotalItem2.Text, fntString, _ Brushes.Black, 550, 470, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 1), 140, 490, 640, 490) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString(cbxItem3.Text, _ fntString, Brushes.Black, 150, 500) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(txtUnitPriceItem3.Text, fntString, _ Brushes.Black, 350, 500, fmtString) e.Graphics.DrawString(txtQuantityItem3.Text, fntString, _ Brushes.Black, 440, 500, fmtString) e.Graphics.DrawString(txtSubTotalItem3.Text, fntString, _ Brushes.Black, 550, 500, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 1), 140, 520, 640, 520) fntString = New Font("Times New Roman", 12, FontStyle.Bold) e.Graphics.DrawString(cbxItem4.Text, _ fntString, Brushes.Black, 150, 530) fntString = New Font("Times New Roman", 12, FontStyle.Regular) e.Graphics.DrawString(txtUnitPriceItem4.Text, fntString, _ Brushes.Black, 350, 530, fmtString) e.Graphics.DrawString(txtQuantityItem4.Text, fntString, _ Brushes.Black, 440, 530, fmtString) e.Graphics.DrawString(txtSubTotalItem4.Text, fntString, _ Brushes.Black, 550, 530, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 2), 140, 550, 640, 550) fntString = New System.Drawing.Font("Times New Roman", 12, _ FontStyle.Bold) e.Graphics.DrawString("Order Summary", fntString, _ Brushes.Black, 260, 600) e.Graphics.DrawLine(New Pen(Color.Black, 2), 220, 620, 560, 620) fntString = New System.Drawing.Font("Times New Roman", _ 10, FontStyle.Bold) e.Graphics.DrawString("Cleaning Total:", fntString, _ Brushes.Black, 260, 630) fntString = New System.Drawing.Font("Times New Roman", _ 10, FontStyle.Regular) e.Graphics.DrawString(txtCleaningTotal.Text, fntString, _ Brushes.Black, 440, 630, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 1), _ 220, 650, 520, 650) fntString = New System.Drawing.Font("Times New Roman", _ 10, FontStyle.Bold) e.Graphics.DrawString("Tax Rate:", fntString, _ Brushes.Black, 260, 660) fntString = New System.Drawing.Font("Times New Roman", _ 10, FontStyle.Regular) e.Graphics.DrawString(txtTaxRate.Text, fntString, _ Brushes.Black, 440, 660, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 1), _ 220, 680, 520, 680) fntString = New System.Drawing.Font("Times New Roman", _ 10, FontStyle.Bold) e.Graphics.DrawString("Tax Amount:", fntString, _ Brushes.Black, 260, 690) fntString = New System.Drawing.Font("Times New Roman", _ 10, FontStyle.Regular) e.Graphics.DrawString(txtTaxAmount.Text, fntString, _ Brushes.Black, 440, 690, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 1), _ 220, 710, 520, 710) fntString = New System.Drawing.Font("Times New Roman", _ 10, FontStyle.Bold) e.Graphics.DrawString("Net Price:", fntString, _ Brushes.Black, 260, 720) fntString = New System.Drawing.Font("Times New Roman", _ 10, FontStyle.Regular) e.Graphics.DrawString(txtNetPrice.Text, fntString, _ Brushes.Black, 440, 720, fmtString) e.Graphics.DrawLine(New Pen(Color.Black, 2), _ 200, 740, 560, 740) End Sub

4. Return to the form
5. From the Printing section of the Toolbox, click PrintDialog and click the form
6. In the Properties window, change its Name to dlgPrint
7. Still in the Properties windows, set its Document property to docPrint
8. On the main menu of the form, click File and double-click Print
9. Implement the event as follows:
    

   Private Sub mnuFilePrint_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) _ Handles mnuFilePrint.Click If dlgPrint.ShowDialog() = DialogResult.OK Then docPrint.Print() End If End Sub

10. Return to the form
11. From the Printing section of the Toolbox, click PrintPreviewDialog and click the form
12. In the Properties window, change its Name to dlgPrintPreview
13. Still in the Properties windows, set its Document property to docPrint
14. On the main menu of the form, click File and double-click Print Preview
15. Implement the event as follows:
     

    Private Sub mnuFilePrintPreview_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) _ Handles mnuFilePrintPreview.Click dlgPrintPreview.ShowDialog() End Sub

16. In the Class Name combo box, select mnuFileExit
17. In the Method Name combo box, select Click and implement the event as follows:
     

    Private Sub mnuFileExit_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) _ Handles mnuFileExit.Click End End Sub

18. Execute the application
19. Open an existing cleaning order and print preview it
     
    
20. Close the form and return to your programming environment

1. Open the Georgetown Dry Cleaner database from this lesson
2. Configure the main form so that, when the user wants to start a new cleaning order, the compiler would check if the value of any control on the form has been changed since the order was started, since the order was opened, or since the last time the order was saved. If any value was changed, a message box should display to let the user know that the cleaning order has been modified and ask whether the user wants to save the cleaning order. If the user answers:
   1. No: The cleaning order would be kept "as is" and a new cleaning order would be started
   2. Yes
      1. If the user was working on a new order, the current new one would be saved with a new receipt number
      2. If the user was working on an order that was previous opened (for example if the customer was coming to pick up a cleaning order and the user had updated the order status), simply save the current cleaning order with its own receipt number
      3. If the user had previously saved the current cleaning order, simply save it again with the same receipt number