Visual Basic Tutorial Lesson 29: Creating Advanced VB database application using ADO control

Lesson 29: Creating Advanced VB database application using ADO control

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In previous lessons, you have learned how to design database applications using data control and ADO control. However, those applications are very simple and plain . In this lesson, you will learn how to create a more advanced database application using ADO control. The application you are going to create is known as an electronic library. This electronic library will be able to accept the user registration as well as handling login command that require the user's password, thus enhancing the security aspect of the database. Basically, the application will constitute a welcome menu, a registration menu, a Login menu and the main database menu. The sequence of the menus are illustrated as follow:

2.1 The Welcome Menu

First of all, you need to design the Welcome menu. You can follow the example as follow:

In this form, you need to insert three command buttons and set their properties as follow:

Propery Name	Setting
Form name	main_menu
command button 1 Name	cmdRegister
command button 1 Caption	Register
command button 2 Name	cmdLogin
command button 2 Caption	Login
command button 3 Name	cmdCancel
command button 3 Caption	Cancel

The code is as follows:

Private Sub cmdCancel_Click()
End
End Sub

Private Sub cmdLogin_Click()
main_menu.Hide
Login_form.Show
End Sub

Private Sub cmdRegister_Click()
main_menu.Hide
Register.Show

End Sub

29.2 The Registration Form

If a new user click the Register button, the registration form will appear. An example is illustrated as follow:

This registration forms consist of two text boxes , three command buttons and an ADO control. Their properties are set as follow:

Propery Name	Setting
Form name	Register
textbox 1 name	txtName
textbox 2 name	txtpassword
textbox 2 PasswordChar	*
command button 1 name	cmdConfirm
command button 1 Caption	Confirm
command button 2 name	cmdClear
command button 2 Caption	Clear
command button 3 name	cmdCancel
command button 3 Caption	Cancel
ADO control name	UserInfo

note that the PasswordChar of textbox 2 is set as * which means users will not be able to see the actual characters they enter, they will only see the * symbol.

The code is as follow:

Private Sub cancel_Click( )
End
End Sub

Private Sub cmdClear_Click( )
txtName.Text = ""
txtpassword.Text = ""

End Sub

Private Sub cmdConfirm_Click()

UserInfo.Recordset.Fields("username") = txtName.Text
UserInfo.Recordset.Fields("password") = txtpassword.Text
UserInfo.Recordset.Update

Register.Hide

Login_form.Show

End Sub

Private Sub Form_Load()
UserInfo.Recordset.AddNew
End Sub
　

29.3 The Login Menu

The Login menu is illustrated as follow:

There are two text boxes and a command button, their properties are set as follow:

Propery Name	Setting
Textbox 1 name	txtName
Textbox 2 name	txtpassword
Command button 1 name	cmdLogin
Command button 1 Caption	Login
Form name	Login_form

The code is as follow:

Private Sub cmdLogin_Click()

Dim usrname As String
Dim psword As String
Dim usernam As String
Dim pssword As String
Dim Msg As String

Register.UserInfo.Refresh
usrname = txtName.Text
psword = txtpassword.Text

Do Until Register.UserInfo.Recordset.EOF
If Register.UserInfo.Recordset.Fields("username").Value = usrname And Register.UserInfo.Recordset.Fields("password").Value = psword Then
Login_form.Hide
frmLibrary.Show
Exit Sub

Else
Register.UserInfo.Recordset.MoveNext
End If

Loop

Msg = MsgBox("Invalid password, try again!", vbOKCancel)
If (Msg = 1) Then
Login_form.Show
txtName.Text = ""
txtpassword = ""

Else
End
End If

End Sub
　

29.4 The Main Database Manager

The main database manager is illustrated as follow:

The properties of all controls are listed in the table below:

Propert Name	Setting
Form name	frmLibrary
ADO control name	adoLibrary
ADO visible	False
TextBox 1 name	txtTitleA
TextBox 2 name	txtAuthor
TextBox 3name	txtPublisher
TextBox 4 name	txtYear
TextBox 5 name	txtCategory
Command button 1 name	cmdSave
Command button 1 caption	&Save
Command button 2 name	cmdNew
Command button 2 caption	&New
Command button 3 name	cmdDelete
Command button 3 caption	&Delete
Command button 4 name	cmdCancel
Command button 4 caption	&Cancel
Command button 5 name	cmdNext
Command button 5 caption	N&ext
Command button 6 name	cmdPrevious
Command button 6 caption	&Previous
Command button 7 name	cmdExit
Command button 7 caption	E&xit

The code is as follow:

Private Sub cmdCancel_Click()
txtTitle.Text = ""
txtAuthor.Text = ""
txtPublisher.Text = ""
txtYear.Text = ""
txtCategory.Text = ""
End Sub

Private Sub cmdDelete_Click()
Confirm = MsgBox("Are you sure you want to delete this record?", vbYesNo, "Deletion Confirmation")
If Confirm = vbYes Then
adoLibrary.Recordset.Delete
MsgBox "Record Deleted!", , "Message"
Else
MsgBox "Record Not Deleted!", , "Message"
End If

End Sub

Private Sub cmdExit_Click()
End
End Sub

Private Sub cmdNew_Click()
adoLibrary.Recordset.AddNew

End Sub

Private Sub cmdNext_Click()
If Not adoLibrary.Recordset.EOF Then
adoLibrary.Recordset.MoveNext
If adoLibrary.Recordset.EOF Then
adoLibrary.Recordset.MovePrevious
End If
End If
End Sub

Private Sub cmdPrevious_Click()
If Not adoLibrary.Recordset.BOF Then
adoLibrary.Recordset.MovePrevious
If adoLibrary.Recordset.BOF Then
adoLibrary.Recordset.MoveNext
End If
End If
End Sub

Private Sub cmdSave_Click()
adoLibrary.Recordset.Fields("Title").Value = txtTitle.Text
adoLibrary.Recordset.Fields("Author").Value = txtAuthor.Text
adoLibrary.Recordset.Update
End Sub
　

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