About Stephen Jackson Expertise I can help with questions regarding VB.NET syntax and object references, with data interfaces and with the design and creation of robust, data aware object classes. I can also be very helpful with creating distributable applications and provide tricks and tips on .msi creation. I also have extensive experience in designing SQL Server Databases and interfacing them with VB.NET. I try to avoid web specific questions, as that is an area of expertise all its own.
Experience
Experience in the Area: I have been a programmer in Visual Basic since version 1.0 and have worked with VB.NET (which is infinitely more powerful than previous versions) since its initial release and SQL Server, both as a corporate IT professional and professional consultant. I first wrote Basic in 1976 on a TRS 80 and have worked in Visual Basic 1.0 and every subsequent release of Microsoft Visual Basic. I worked for over 7 years as a Senior Level Consultant in the area and currently hold a Project Manager position in IT.
Education and Credentials: MBA in Econometrics, 1983, University of Memphis.
BBA in Financial Management, 1982, Fogelman College of Business and Economics, University of Memphis. Microsoft Certified Professional
Areas of Special Expertise:
My specialty is the design of Object Oriented Solutions with robust, data aware object classes. I generally avoid the classic ‘Three Tier’ model as I find it redundant and cumbersome to maintain. I also specialize in the creation of ‘User Friendly’ User Interfaces which help lessen the need for user training and help prevent user error. I work best with Windows Forms based applications, and while I do work in C# as well, I prefer to limit my questions here to Windows Forms based applications created in Visual Basic.NET and SQL Server. I wil also address questions relating to the distribution and installation of Windows Forms based applications created in VB.NET.
Expert: Stephen Jackson Date: 4/23/2008 Subject: VB.NET 2008. Default login form not functioning
Question QUESTION: Hi Stephen, how are you?
May you help me with this little task please?
I have done the default login form in VB.NET 2008 and the code has no errors but whenever I run the form, i always get for whatever action the messsagebox " you must enter a username" , besides the cancel button is not functionning.
Public Class LoginForm
Inherits System.Windows.Forms.Form
' TODO: Insert code to perform custom authentication using the provided username and password
' (See http://go.microsoft.com/fwlink/?LinkId=35339).
' The custom principal can then be attached to the current thread's principal as follows:
' My.User.CurrentPrincipal = CustomPrincipal
' where CustomPrincipal is the IPrincipal implementation used to perform authentication.
' Subsequently, My.User will return identity information encapsulated in the CustomPrincipal object
' such as the username, display name, etc.
Private Sub LoginForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
InitializeComponent()
End Sub
Private Sub OK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK.Click
Dim AuthenticationReader As System.Data.SqlClient.SqlDataReader
'Intitalizes connection object
Dim SqlConnection As New SqlClient.SqlConnection
SqlConnection.ConnectionString = "Server=owner;database=***"
'Initializes command object to execute statements.
Dim AuthenticationCommand As New SqlClient.SqlCommand
AuthenticationCommand.Connection = SqlConnection
'Declarations
Dim DBusername As String
Dim DBuserpassword
Dim DBuserID As Integer
Dim DBlogggedname As String
Dim DBprivilege As String
If UsernameTextBox.Text.Length = 0 Then
MessageBox.Show("You must enter a username", "Invalid Username", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
UsernameTextBox.Focus()
ElseIf PasswordTextBox.Text.Length = 0 Then
MessageBox.Show("You must enter a password", "Invalid Password", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
PasswordTextBox.Focus()
Else
AuthenticationReader = AuthenticationCommand.ExecuteReader()
If AuthenticationReader.HasRows Then
While (AuthenticationReader.Read())
DBusername = AuthenticationReader("UserName")
DBuserpassword = AuthenticationReader("Password")
DBuserID = AuthenticationReader("UserID")
DBlogggedname = AuthenticationReader("Name")
DBprivilege = Trim(AuthenticationReader("Privilege"))
End While
Else
MessageBox.Show("Invalid username!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
UsernameTextBox.Focus()
Exit Sub
End If
AuthenticationReader.Close()
SqlConnection.Close()
If bHashEquals(hashedBytes, DBuserpassword) Then
Dim Frame As New Frame()
Frame.Show()
Me.Hide()
Else
MessageBox.Show("Invalid password!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
PasswordTextBox.Focus()
End If
End If
End Sub
Private Function bHashEquals(ByVal byHash1 As Byte(), ByVal byHash2() As Byte) As Boolean
bHashEquals = False
If byHash1.Length = byHash2.Length Then
Dim i As Integer
Do While (i < byHash1.Length) AndAlso (byHash1(i) = byHash2(i))
i = i + 1
Loop
If i = byHash1.Length Then
bHashEquals = True
End If
End If
End Function
Private Sub Cancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Cancel.Click
Me.Close()
End Sub
End Class
Regards
ANSWER: Carolina,
I sent myself a reminder to look up the answer to this tomorrow .. please forgive me forgetting today as I had planned!
You are most kind with your reviews; thank you! If you had a feather, you would have tickled me to death :c)
Stephen
Carolina,
OK, I am looking this over .. it may take a bit of back and forth to find the issue. I see that this code logs into a SQL Server ... correct? It looks as though this code has no reference to a specific instance or database. This may be why it does not work ... do you have SQL Server? If so, then you will need to reference the server and the database in the 'SqlConnection.ConnectionString = "Server=owner;database=***"' line. Now if you do not, then we know the problem :c)
Just bear with me; we will get to the bottom of this!
Stephen
---------- FOLLOW-UP ----------
QUESTION: Thank u Stephen, u r very kind and i am honored to meet u.
In fact i would like to tell u to not bother yourself with this issue anymore cause i resolved it, the problem was in the configuration of SQL.
If I had further questions, i would like to ask u about them.
Best Regards
Answer Carolina,
That is great! I am glad you got it taken care of and hope I at least helped a little (sometimes you only need a little help). It is a pleasure to meet you, too, and always feel free to ask anything you like ....
