Lesson 22: Creating an Advanced VB database application using ADO control

　

In previous lessons, you have learned to design database applications using data control and ADO control. However, those are very simple and plain applications. In this lesson, you will learn to create a more advance 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 users' registration as well as handling login command that require the use of 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:



　

　



　

　

　

　

　

　

　

　

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:

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 codes are as follow:

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

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:

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 codes are 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

　

The Login menu is illustrated as follow:

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

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

The codes are 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
　

The main database menu is illustrated as follow:

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

　

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 codes are 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
　

[Back to Content Page]