Glad you asked. The problem is that EF Core team doesn’t (and does not want to) provide GroupJoin translation. See my comments on this EF Core GitHub thread Query: Support GroupJoin when it is final query operator #19930 and linked discussions where I was trying to convince them to include such support (which should have … Read more
This should do the trick var query = from a in context.TableA from b in context.TableB .Where(x => x.TableA_Id == a.Id) .OrderBy(x => x.Value) .Take(10) where a.Key >= 0 && a.Key <= 999 select new { a.Key, b.Value, };
If you need to do the Left joins then you have to use into and DefaultIfEmpty() as shown below. var result = from person in _dbContext.Person join detail in _dbContext.PersonDetails on person.Id equals detail.PersonId into Details from m in Details.DefaultIfEmpty() select new { id = person.Id, firstname = person.Firstname, lastname = person.Lastname, detailText = m.DetailText … Read more
You can’t do that with a LINQ joins – LINQ only supports equijoins. However, you can do this: var query = from e in entity.M_Employee from p in entity.M_Position where e.PostionId >= p.PositionId select p; Or a slightly alternative but equivalent approach: var query = entity.M_Employee .SelectMany(e => entity.M_Position .Where(p => e.PostionId >= p.PositionId));
Since you want to see if search contains a word which is contained in the description of p you basically need to test for each value in search if it is contained in the description of p result = from p in products where search.Any(val => p.Description.Contains(val)) select p; This is c# syntax for the … Read more
Well, you can just put multiple “where” clauses in directly, but I don’t think you want to. Multiple “where” clauses ends up with a more restrictive filter – I think you want a less restrictive one. I think you really want: DataTable tempData = (DataTable)grdUsageRecords.DataSource; var query = from r in tempData.AsEnumerable() where r.Field<string>(“UserName”) != … Read more
Use where list.Contains(item.Property) Or in your case: var foo = from codeData in channel.AsQueryable<CodeData>() where codeIDs.Contains(codeData.CodeId) select codeData; But you might as well do that in dot notation: var foo = channel.AsQueryable<CodeData>() .Where(codeData => codeIDs.Contains(codeData.CodeId));
Thank you for reporting this issue. Yes, it is not expected to see both joins. This is a bug that has been fixed in the current (not yet released) bits. In the current bits the same query produces: SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name], [Extent1].[ContactId] AS [ContactId], … [Extent2].[Id] AS [Id1], .. [Extent2].[FirstName] AS … Read more
Don’t throw away the return value. The OrderBy extension method is does not mutate the input. Try: newView = newView.OrderBy(x => x.viewed); There is no reason why that won’t work, assuming the viewed value is correct. Also, make sure that OrderBy is after any operations (e.g. Distinct) which will ruin ordering. Happy coding!
It makes more sense to ask about a particular aspect of LINQ. It’s a bit like asking “How Windows works” otherwise. The key parts of LINQ are for me, from a C# perspective: Expression trees. These are representations of code as data. For instance, an expression tree could represent the notion of “take a string … Read more