title: linq left join datatable and oder by the nullable value
body: <pre><code>var query = from detail in dsApp.AsEnumerable()
          join rate in dsRate.AsEnumerable()
          on detail.Field&lt;string&gt;("ApplicationName") equals
                rate.Field&lt;string&gt;("AppName")
          into g
          from h in g.DefaultIfEmpty()
          orderby  ...
          select new { A = detail, B = (h==null? 0: h.Field&lt;int&gt;("num")) };
  </code></pre>
  
  <p>For the above query, how can I orderby the  B?
  Thanks</p>