FAQ: How do I create a Login Verification routine (Login Form) and make the password case sensitive?

Question

How do I create a Login Verification routine (Login Form) and make the password case sensitive?

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.

Answer 1

Here is the walkthrough:

1)  e.g. MS Access Database file myDB.mdb contains a Users table with the following two fields:

Field Name   Data Type

Username     Text

Password      Text

 

2)  Create a new Windows Forms application, then add a “Login Form” template:

Project menu-> Add Windows Form -> Select "Login Form" template

 

3)  Code sample

Prerequisites: txtUsername TextBox, txtPassword TextBox, OK button and Cancel button on Login Form.

 

Imports System.Data.OleDb
Public Class LoginForm1
    ' OK button   
    Private Sub OK_Click(ByVal sender As System.Object, _
                   ByVal e As System.EventArgs) Handles OK.Click
        Dim con As New OleDbConnection("Provider=Microsoft.jet.oledb.4.0;data source=D:\myDB.mdb")
        Dim cmd As OleDbCommand = New OleDbCommand( _
                   "SELECT * FROM Users WHERE Username = '" & _
                   txtUsername.Text & "' AND [Password] = '" & txtPassword.Text & "' ", con)
        con.Open()
        Dim sdr As OleDbDataReader = cmd.ExecuteReader()
        ' If the record can be queried, it means passing verification, then open another form.   
        If (sdr.Read() = True) Then
            MessageBox.Show("The user is valid!")
            Dim mainForm As New MainForm
            mainForm.Show()
            Me.Hide()
        Else
            MessageBox.Show("Invalid username or password!")
        End If
    End Sub
    ' Cancel button   
    Private Sub Cancel_Click(ByVal sender As System.Object, _
                    ByVal e As System.EventArgs) Handles Cancel.Click
        Me.Close()
    End Sub
End Class

 

Related threads:

http://social.msdn.microsoft.com/forums/en/vbgeneral/thread/4eb4dc84-a62f-4a46-95b0-3b981fb83f23/

http://social.msdn.microsoft.com/Forums/en/vbgeneral/thread/20a1564c-77ac-4972-9e23-840d63f7622f

 

Note: The password in the TextBox is not case sensitive in the above code sample.

 

To make the password case sensitive, try this workaround:

First retrieve the password from database into DataReader object, and then compare it with txtPassword.Text outside T-SQL statement.

 

Imports System.Data.OleDb
Public Class LoginForm1
    Private Sub OK_Click(ByVal sender As System.Object, _
                   ByVal e As System.EventArgs) Handles OK.Click
        Dim con As OleDbConnection = New OleDbConnection( _
                   "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\myDB.mdb;")
        Dim cmd As OleDbCommand = New OleDbCommand( _
                   "SELECT * FROM Users WHERE Username='" & _
                   txtUsername.Text & "' and [Password]='" & txtPassword.Text & "'", con)
        con.Open()
        Dim sdr As OleDbDataReader = cmd.ExecuteReader()
        ' It will be case sensitive if you compare passwords here.   
        If sdr("Password") <> txtPassword.Text.ToString() Then
            MessageBox.Show("Invalid password!")
        End If
        sdr.Close()
        con.Close()
    End Sub
End Class

 

Related thread:

http://social.msdn.microsoft.com:80/Forums/en/vbgeneral/thread/cb2e617a-d226-4b20-bff3-11180dfe1b71/

 

For more FAQ about Visual Basic .NET General, please see Visual Basic .NET General FAQ

 

 

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.

Answer 2

Hi Xiao Yun,

I wonder if you could prepare a walkthrough for Microsoft SQL server? I am using SQL server 2005 express edition :) Thanks a lot!

---

Thank you, msdn =) 99.9% of my questions have been answered :D

Answer 3

The Login Verification Logic/Routine is still applicable to SQL Server database file.

What you need to do is:
1. Use System.Data.SqlClient instead of System.Data.OleDb namespace
2. Replace such OleDb* classes as OleDbConnection, OleDbCommand, OleDbDataAdapter with corresponding Sql* classes such as SqlConnection, SqlCommand, SqlDataAdapter.
Code sample: How to connect and access SQl Server database and MS Access database in VB.NET
http://social.msdn.microsoft.com/forums/en-US/Vsexpressvb/thread/5980181e-f666-4f0a-ab50-c4ebecf96f02/
3. Change database connection string.
     Some connection strings for SQL Server 2005
     http://www.connectionstrings.com/sql-server-2005

 

The walkthrough for Microsoft SQL Server database:

1)  e.g. Prepare a SQL Server database file myDB.mdf containing a Users table with the following two fields:

Field Name   Data Type

Username     VarChar(20)

Password     VarChar(20)

 

2)  Create a new Windows Forms application, then add a “Login Form” template:

     Project menu-> Add Windows Form -> Select "Login Form" template

 

3)  Code sample

Prerequisites: txtUsername TextBox, txtPassword TextBox, OK button and Cancel button on Login Form.

Imports System.Data.SqlClient
Public Class LoginForm1
    ' OK button   
    Private Sub OK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK.Click
        Dim con As New SqlConnection("Data Source=.;Integrated Security=True;AttachDbFilename=D:\myDB.mdf")
        Dim cmd As New SqlCommand("SELECT * FROM Users WHERE Username = '" & txtUsername.Text & "' AND [Password] = '" & txtPassword.Text & "' ", con)
        con.Open()
        Dim sdr As SqlDataReader = cmd.ExecuteReader()
        ' If the record can be queried, it means passing verification, then open another form.   
        If (sdr.Read() = True) Then
            MessageBox.Show("The user is valid!")
            Dim mainForm As New MainForm
            mainForm.Show()
            Me.Hide()
        Else
            MessageBox.Show("Invalid username or password!")
        End If
    End Sub
    ' Cancel button   
    Private Sub Cancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Cancel.Click
        Me.Close()
    End Sub
End Class

Best regards,
Martin Xie

 

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.