Option Explicit On
Imports System.Data.SqlClient
Imports System.Data
 
    Public Function GetConnection() As SqlConnection
        'Variablendeklaration
        Dim conString As String
        conString = "Server=dev-pc\SQLEXPRESS;database=testdba;User" & _
          "ID=dbauser;Pwd=dbauserpw1"
        Dim con As SqlConnection = Nothing
 
        Try
            con = New SqlConnection(conString)
            con.Open()
        Catch ex As Exception
            Throw (ex)
        End Try
        Return (con)
    End Function

    Private Sub OK_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles OK.Click
        'Variablendeklaration
 
        'Stop
        Dim benutzer As String
        Dim passwort As String
        Dim con As SqlConnection = GetConnection()
        Dim sql As String
 
        Dim Username As String
        Dim Password As String
        Dim Aktiv As Boolean
        Dim dr As SqlDataReader
 
        Username = Nothing
        Password = Nothing
        Aktiv = False
        benutzer = Nothing
        passwort = Nothing
 
        benutzer = UsernameTextBox.Text
        passwort = PasswordTextBox.Text
 
        If benutzer = "" Or passwort = "" Then
            MsgBox("Benutzername und Passwort müssen eingegeben werden!", _
              MsgBoxStyle.Critical)
        Else
            sql = "SELECT * FROM dbo.Benutzer WHERE Username="
 
            Dim cdo As New SqlCommand(sql & benutzer, con)
 
            dr = cdo.ExecuteReader
            con.Close()
            If dr.Read <> Nothing Then
                Username = dr.Item(4).ToString
                Password = dr.Item(5).ToString
                Aktiv = dr.Item(8).ToString
 
            End If
 
            If benutzer = Username And passwort = Password And Aktiv = True Then
                Me.Close()
                Anwendung.Show()
            ElseIf benutzer = Username And passwort = Password And Aktiv = _
              False Then
                MsgBox("Dieser Account ist deaktiviert worden! Bitte setzen Sie" & _
                "sich mit Ihrem Administrator in Verbindung!", _
                MsgBoxStyle.Critical)
                UsernameTextBox.Text = ""
                PasswordTextBox.Text = ""
            Else
                MsgBox("Benutzername oder Passwort stimmen nicht überein! Bitte" & _
                  "geben Sie Ihre Zugangsdaten erneut ein! Achten Sie bitte auf" & _
                  "die Schreibweise", MsgBoxStyle.Critical)
                UsernameTextBox.Text = ""
                PasswordTextBox.Text = ""
            End If
        End If
    End Sub