Correct creation of a database TreeView in WPF MVVM
<p>In Microsoft SQL Server I have table like this:</p>

<pre><code>Article    Type1    Type2       Type3      Name             Cost
----------------------------------------------------------------
ABC.100    Part     From box    Null       Board            300
ABC.200    Part     From fence  From blue  Another board    200
ABC.098    Null     Null        From blue  Thing            120
ABC.001    Blank    From box    Null       Board1           -12
</code></pre>

<p>There are no relationships, all in a single table.</p>

<p>How to correctly set up the TreeView as such:</p>

<ul>
<li>Database

<ul>
<li>Type1

<ul>
<li>Type2

<ul>
<li>Type3</li>
</ul></li>
</ul></li>
</ul></li>
</ul>

<p>When, selecting any "type" display table with rows according to Type/1/2/3</p>