login form

Question

hi. i have a windows form application with a login form. here is the code for that form:

Imports System.Data.SqlClient
 
Public Class LoginForm1
 
    ' 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.
 
    'Dim con As New Data.SqlClient.SqlConnection
    'Dim cmd As New Data.SqlClient.SqlCommand
    
    'Dim sdr As SqlDataReader
 
    Private Sub OK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK.Click
        Stop
        Dim con As New Data.SqlClient.SqlConnection("Data Source=69.175.122.58,8888;Initial Catalog=CustomerTicks4;Persist Security Info=True;User ID=danwo;Password=dan58wo")
        Dim cmd As New Data.SqlClient.SqlCommand("Select * From tblUsers Where txtUserName= UserNameTextBox.Text AND txtPassword= PasswordTextBox.Text,con")
        
        con.Open()
        
        Dim sdr As SqlDataReader = cmd.ExecuteReader 'this error occurs here: ExecuteReader: Connection property has not been initialized.
 
 
 
 
 
        ' 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()
 
        'If sdr.Read = True Then
        'MessageBox.Show("The user is valid!")
 
 
 
 
        'End If
 
 
    End Sub
 
    Private Sub Cancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Cancel.Click
        Me.Close()
    End Sub
 
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        My.Forms.AddUserForm.Show()
 
 
    End Sub
End Class

---

Dan Wojtasiewicz

Answer 1

Hi Dan,

Welcome to the MSDN forum.

What's the problem you're facing? Please clarify your question, we're glad to help you.

Have a nice day!

---

Shanks Zen
MSDN Community Support | Feedback to us

Answer 2

Private Sub btn_Ok_Click(sender As Object, e As EventArgs) Handles btn_Ok.Click

        Dim myConn As OleDbConnection
        Dim myCmd As OleDbCommand
        Dim myDr As OleDbDataReader
        Dim myDT As New DataTable

        myConn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\Database File\PulsaHP.mdb")
        myConn.Open()
        myCmd = New OleDbCommand("SELECT Nama,Password,UserLevel FROM Pengguna WHERE Nama='" & tb_User.Text & "' AND Password='" & tb_Pass.Text & "'", myConn)
        myDr = myCmd.ExecuteReader
        myDT.Clear()
        myDT.Load(myDr)
        Try
            If myDT.Rows(0)(0).ToString = tb_User.Text And myDT.Rows(0)(1).ToString = tb_Pass.Text Then
                If myDT.Rows(0)(2).ToString.ToLower = "1" Then
                    'code if the user login as administrator
                Else
                    'code if user login as standard user
                End If

                MessageBox.Show("Login Success")
            End If
        Catch ex As Exception
            MessageBox.Show("LogIn Failed")
        End Try

that my example, on your code you are wrong type the command 

Dim cmd As New Data.SqlClient.SqlCommand("Select * From tblUsers Where txtUserName= UserNameTextBox.Text AND txtPassword= PasswordTextBox.Text,con")

the correct one is :

Dim cmd As New Data.SqlClient.SqlCommand("Select * From tblUsers Where txtUserName= UserNameTextBox.Text AND txtPassword= PasswordTextBox.Text",con)