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我是 LINQ 新手，我有这个查询，它返回调查中的页面。（无论出于何种原因，这些值都没有具体化到表中。）

//Group all of this data by page 
var pages = from fq in db.FormQuestions
        where (fq.FormId == id) && fq.Disabled == false
        group fq by fq.PageNumber into p
        select new DTOs.PageDTO { PageNumber = p.Key.Value };

然后我有这个查询，它将所有的叶子数据投影到 DTO 中。

var questions = from fq in db.FormQuestions
   join q in db.Questions on fq.QuestionId equals q.QuestionId
   where (fq.FormId == id) && fq.Disabled == false
   //where (fq.FormId == id) && fq.Disabled == false && fq.PageNumber == page
   orderby fq.DisplayOrder
   select new DTOs.FormQuestionDTO()
   {
       DisplayOrder = (fq.DisplayOrder.HasValue ? fq.DisplayOrder.Value : 0),
       PageNumber = (fq.PageNumber.HasValue ? fq.PageNumber.Value : 0),
       QuestionId = q.QuestionId,
       QuestionSelectionMode = q.vts_tbQuestionSelectionMode.Description,
       QuestionText = q.QuestionText,
       Answers =
           from answer in q.Answers
           join at in db.AnswerTypes on answer.AnswerTypeId equals at.AnswerTypeID
           where answer.Disabled == false
           orderby answer.DisplayOrder
           select new DTOs.AnswerDTO()
           {
               AnswerId = answer.AnswerId,
               AnswerText = answer.AnswerText,
               DisplayOrder = answer.DisplayOrder,
               AnswerType = at.Description
           }
   };

有没有办法巧妙地加入这两个？即，在每个页面 DTO 下，我想查看 QUEstion DTO，然后在该 Answer DTO 内部，然后……

此外，即使我可以在一个 LINQ 语句中完成所有这些操作，是否最好单独构建 LINQ 语句然后合并它们？这感觉有点像在 SQL 中构建临时变量，因为它可能构建一个巨大的查询，但维护起来很痛苦。

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1 回答 1

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那么为什么不这样的工作呢？

//Group all of this data by page 
var pages = from fq in db.FormQuestions
        where (fq.FormId == id) && fq.Disabled == false
        group fq by fq.PageNumber into p
        select new DTOs.PageDTO { 
          PageNumber = p.Key.Value 
          questions = from fq in db.FormQuestions
                     join q in db.Questions on fq.QuestionId equals q.QuestionId
                     where (fq.FormId == id) && fq.Disabled == false
                     orderby fq.DisplayOrder
                     select new DTOs.FormQuestionDTO()
                     {
                       DisplayOrder = (fq.DisplayOrder.HasValue ? fq.DisplayOrder.Value : 0),
                       // etc as you 2nd code sample
于 2012-12-29T23:25:59.687 回答