Private Sub cbo_SelectUser_SelectedValueChanged(sender As Object, e As _
  EventArgs) Handles cbo_SelectUser.SelectedValueChanged
        cbo_SelectUser.Text.ToString() ' Gefüllte Combobox mit übergabe
        DB_SQL = "SELECT UserName(" & _
          "cbo_SelectUser.Text.ToString),Kuerzel,Pass,SysRoll FROM user" 'SQL 
        ' Abfrage nach user Auswahl
        DB_Command.CommandText = DB_SQL
        DB_Conn_Open()
        DB_Command.ExecuteReader()
        While (DB_Reader.Read())
            txb_Username.Text = (DB_Reader("UserName")) 'Benutzername
            txb_Kuerzel.Text = (DB_Reader("Kuerzel")) 'Benutzerkürzel
            txb_Password.Text = (DB_Reader("Pass")) 'Passwort
            cbo_Sysroll.Text = (DB_Reader("SysRoll"))'Systemrolle
        End While
        DB_Conn_Close()
    End Sub