title: how to do linq to sql String Join?
body: <p>I want to combine the name of the list in the list.
  Error Message : LINQ to Entities does not recognize the method 'System.String Join(System.String, System.String[])' method, and this method cannot be translated into a store expression.</p>
  
  <pre><code>dgv.DataSource = this.oFacade.Context.Books
                                           .Include(c =&gt; c.Categories)
                                          .Select(c =&gt; new dtoObjectDGV
                                          {
                                              ID = c.ID,
                                              Name = c.Name,
                                              CategoryInfo= String.Join(", ", c.Categories.Select(d =&gt; d.Name).ToArray())
                                          }).ToList();
  </code></pre>
  
  <p>result : Name = C# Book CategoryInfo = X Category, Y Category,... bla bla</p>