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For In here how it goes var Userlist = new List<Int32> { 560, 561, 511, 611 }; var User= context.GetTable<Users>(); var q = (from p in User where Userlist.Contains(p.int_UserId) select p); For Not In here how it goes var Userlist = new List<Int32> { 560 }; var User= context.GetTable<Users>(); var q = (from p in User where !Userlist.Contains(p.int_UserId) select p);

By Using DefaultIfEmpty() extension method you can check the sequence for empty and return something for it and do some manipulation on it afterwards. For example var numbers = new int[] {1,2,3,4,5,6,7}; Console.WriteLine(numbers.DefaultIfEmpty().Sum()); If the sequence is empty it will return 0 otherwise it will sum and return that. By Default if you want to return some value other then 0 it will return that as well Console.WriteLine(numbers.DefaultIfEmpty(100).Sum()); In this case it will return 100 if the sequence is empty.

Let's have a scenario in which there are two tables Teachers and Teacher_Courses .Teachers are assigned courses having teacherid in Teacher_Courses table as the foreign key. So to pick up all the Teacher's list with no of courses assigned regardless of having been assigned a course or not in linq you will be using left outer join as follows. using (TeacherContext context = new TeacherContext()) { var Teachers = context.Teachers; var TeacherCourse = context.TeacherCourses; var q = from c in Teachers join o in TeacherCourse on c.int_TeacherId equals o.int_TeacherId into j from Course in j.DefaultIfEmpty().GroupBy(m=>m.int_TeacherId) select new { Teachers = c.vcr_TeacherName, Courses = Course.Count() == 0 ? "(no Courses Assigned)" : Course.Where(m => m.int_TeacherId == c.i...