在linq查詢中使用子查詢

Question

如何在linq查詢中構造以下sql查詢以獲取結果？

SELECT PageNumber from LMS_SurveyQuestion WHERE SurveyQuestionID IN
(SELECT  SurveyQuestionID from LMS_SurveyQuestionOptionChoice 
WHERE NextPageNumber = 4) and SurveyID = 1

Answer 1

嘗試這個

var result = from l in LMS_SurveyQuestion 
             let lsq = from l_S in LMS_SurveyQuestionOptionChoice 
             where l_S.NextPageNumber = 4
             select l_S.SurveyQuestionID 
             where lsq.Contains(l.SurveyQuestionID) and l.surveyid = 1
             select l.PageNumber;  

Answer 2

看一下這篇文章 。 基本上，如果要在LINQ中實現SQL IN查詢，則需要先構造一個內部查詢，然后再使用Contains（）方法。 這是我的嘗試：

var innerQuery = (from log in LMS_SurveyQuestionOptionChoice where log.NextPageNumber = 4 select log.SurveyQuestionID);

var result = (from f in LMS_SurveyQuestion where innerQuery.Contains(f.SurveyQuestionID) && f.SurveyID = 1 select f);

希望這會有所幫助。