Question

I have a login form for my program and it works fine but when i input an username and password that is not in my database, the textbox for the username and password just clears the text and does not show the messagebox that says “incorrect username/password”

Here is my code:

 Dim con As OleDbConnection = New OleDbConnection( _
               "Provider=Microsoft.Jet.OLEDB.4.0;Data Source= UserPass.mdb;")
    con.Open()
    Dim str As String
    str = "SELECT * FROM UserPass WHERE Username='" & txtUsername.Text & "' AND Password='" & txtPassword.Text & "'"
    Dim cmd As OleDbCommand = New OleDbCommand(str, con)
    cmd.Parameters.AddWithValue("user", txtUsername.Text)
    cmd.Parameters.AddWithValue("pass", txtPassword.Text)
    Dim sdr As OleDbDataReader = cmd.ExecuteReader()
    ' It will be case sensitive if you compare usernames here.   
    If sdr.HasRows Then
        If sdr.Read Then
            If txtPassword.Text <> sdr("Password").ToString Or txtUsername.Text <> sdr("Username").ToString Then
                MessageBox.Show(" Incorrect Username/Password. Login Denied ", " Error! ", MessageBoxButtons.OK, MessageBoxIcon.Error)
            Else
                MessageBox.Show(" You are now Logged In! ", " Welcome! ", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
                frmOne.Show()
                Me.Hide()
            End If
        End If
    End If

How can i make my program show a messagebox when i input a username and password that is not in my database?

Answer 1

The Line sdr.HasRows doesn’t look like it would fire. On your select statement it won’t have rows if username and password don’t match.

Consider changing the code to this :

If sdr.HasRows Then
    If sdr.Read Then
            MessageBox.Show(" You are now Logged In! ", " Welcome! ", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
            frmOne.Show()
            Me.Hide()
    End If
Else
    MessageBox.Show(" Incorrect Username/Password. Login Denied ", " Error! ", MessageBoxButtons.OK, MessageBoxIcon.Error)
End If