CSharp/DBconnection/MainWindow.xaml

<Window x:Class="DBconnection.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:DBconnection"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Button Content="TEST" HorizontalAlignment="Left" Margin="256,320,0,0" VerticalAlignment="Top" Width="274" Height="65" FontWeight="Bold" FontSize="48" Click="Button_Click"/>
        <ListBox x:Name="lista" HorizontalAlignment="Left" Height="208" Margin="110,52,0,0" VerticalAlignment="Top" Width="580"/>
        <Button x:Name="Allusersbutton" Content="AllUsers" HorizontalAlignment="Left" Height="23" Margin="623,273,0,0" VerticalAlignment="Top" Width="67" Click="Allusersbutton_Click"/>

    </Grid>
</Window>