Linq Query

Question

Hi

I am trying below query. I want only those books from t2 which have BookRpl = 4 and does not exists in View_SessionBookPlanningRecommendations for students (1,17,18)

                    LMSDBDataContext context = new LMSDBDataContext();
                    var objResult = (from t in context.View_SessionBookPlanningRecommendations
                                     from t2 in context.View_BookDetails
                                     from t3 in context.StudentDetails
                                     where (int)t.BookID == (int)t2.ID
                                     && t2.BookRPL == "4"
                                     
                                     && t.BookID != 65
                                     orderby t.Name
                                     select new
                                     {
                                         t.GroupName,
                                         t.SessionDate,
                                         t.BookTitle,
                                         t.MentorName,
                                         t.Name
                                     }).ToList();

Thanks

Naimish Makwana · Answer

Try below: LMSDBDataContext context = new LMSDBDataContext(); int[] studentIds = new int[] { 1, 17, 18 }; // dynamic student IDs var objResult = (from t2 in context.View_BookDetails where t2.BookRPL == "4" && !context.View_SessionBookPlanningRecommendations .Any(r => r.BookID == t2.ID && studentIds.Contains(r.StudentID)) orderby t2.BookTitle select new { t2.BookTitle, t2.Author, t2.Publisher }).ToList(); In this modified query, we first declare a collection of student IDs (in this case, an array of integers). Then we use the Contains method with the studentIds collection to check if the book has a recommendation for any of the specified students. Note that the studentIds collection can be populated dynamically based on user input or other requirements. Thanks

Naimish Makwana · Answer

Try below query: LMSDBDataContext context = new LMSDBDataContext(); var objResult = (from t2 in context.View_BookDetails where t2.BookRPL == "4" && !context.View_SessionBookPlanningRecommendations .Any(r => r.BookID == t2.ID && (r.StudentID == 1 || r.StudentID == 17 || r.StudentID == 18)) orderby t2.BookTitle select new { t2.BookTitle, t2.Author, t2.Publisher }).ToList(); Thanks

Ramco Ramco · Answer

Hi It is giving error - cannot convert from int? to string List StudentCollectionList = new List (); BALGroupParticipant bALGroupParticipant = new BALGroupParticipant(); if (GroupCollection.Count > 0) { List Result = bALGroupParticipant.GetGroupParticipantList(GroupCollection); if (Result != null) { foreach (var colum in Result) { StudentCollectionList.Add(colum.StudentID.ToString()); } } } Thanks

Naimish Makwana · Answer

Use this LMSDBDataContext context = new LMSDBDataContext(); List StudentCollectionList = new List (); // code to populate StudentCollectionList var objResult = (from t2 in context.View_BookDetails where t2.BookRPL == "4" && !context.View_SessionBookPlanningRecommendations .Any(r => r.BookID == t2.ID && StudentCollectionList.Select(int.Parse).Contains(r.StudentID)) orderby t2.BookTitle select new { t2.BookTitle, t2.Author, t2.Publisher }).ToList();

Ramco Ramco · Answer

Hi Naimish How i can use studentcollectionlist in Linq Query List StudentCollectionList = new List (); BALGroupParticipant bALGroupParticipant = new BALGroupParticipant(); if (GroupCollection.Count > 0) { List Result = bALGroupParticipant.GetGroupParticipantList(GroupCollection); if (Result != null) { foreach (var colum in Result) { StudentCollectionList.Add(colum.StudentID.ToString()); } } } Thanks

Ramco Ramco · Answer

Hi Naimish Student Id will be dynamic. Thanks