title: LINQ, can't join to string
body: <p>I have a list of users, each user has list of questions. In my model list of questions should be in string via comma. I try:</p>
  
  <pre><code>public List&lt;ITW2012Mobile.ViewModels.AdminSurveyReportModel&gt; SurveyReportList()
  {
      var q = from i in _dbContext.Users
              where i.UserId != null
              select new ITW2012Mobile.ViewModels.AdminSurveyReportModel()
              {
                  FirstName = i.FirstName,
                  LastName = i.LastName,
                  Question4 = String.Join(", " , (from a in _dbContext.MultipleQuestions where a.MultipleQuestionType.KEY == MultipleQuestionKeys.BENEFITS select a.Question).ToArray())
              };
      return q.ToList();
  }
  
  public class AdminSurveyReportModel
  {
      public string FirstName { get; set; }
      public string LastName { get; set; }
      public string Question4 { get; set; }
  }
  </code></pre>
  
  <p>of course, I get error:</p>
  
  <blockquote>
    <p>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>
  </blockquote>
  
  <p>How to get it correctly?</p>