title: How to select cascading DropDownList with SqlDataSource
body: <p>I have the following in my data base -    </p>
  
  <pre><code>breedId Species Breed
  0       dog      Alsatian
  1       dog      pitbull
  2       dog      Shetland sheepdog
  3       dog      Boxer
  4       cat      Dragon Li
  5       cat      Australian Mist
  6       cat      Korat
  </code></pre>
  
  <p>In the c# designer view, I have 2 drop-down list one which has species and other for breed.</p>
  
  <p><strong>What I want is that</strong> when user picks 'dog' in species list,
  the breed list should have the following <code>Alsatian, pitbull, Shetland sheepdog,Boxer</code></p>
  
  <p>At the moment when I pick 'dog', all the breed from the database is shown.</p>
  
  <pre><code>&lt;asp:DropDownList ID="DropDownListSpecies" runat="server" 
       Height="27px" Width="107px" DataSourceID="hs330" 
       DataTextField="Species" DataValueField="Species"&gt;
  &lt;/asp:DropDownList&gt;
  &lt;asp:SqlDataSource ID="Species" runat="server" 
       ConnectionString="&lt;%$ ConnectionStrings:ConnectionString %&gt;" 
       SelectCommand="SELECT DISTINCT [Species] FROM [Breed]"&gt;
  &lt;/asp:SqlDataSource&gt;
  
  &lt;asp:DropDownList ID="DropDownListBreed" runat="server" Height="20px" 
      Width="110px" DataSourceID="breed" DataTextField="Breed" 
      DataValueField="Breed"&gt;
  &lt;/asp:DropDownList&gt;
  &lt;asp:SqlDataSource ID="breed" runat="server" 
      ConnectionString="&lt;%$ ConnectionStrings:ConnectionString %&gt;" 
      SelectCommand="SELECT DISTINCT [Breed] FROM [Breed]"&gt;
  &lt;/asp:SqlDataSource&gt;
  </code></pre>