ObjectQuery lambda expression for select inside select
i want to开发者_开发知识库 create query like this using lambda expression in ObjectQuery
SELECT *
FROM tableA
WHERE ID in (SELECT ID in tableB)
I try using
var histories = _entities.ProductViewHistories.Take(5).OrderByDescending(p=>p.DateViewed);
var products = _entities.Products.Where(p => p.ID in histories );
but it's not working. Can someone point me to the right direction?
Thanks
Sure - "in" isn't part of C# in that way. Try this though:
var products = _entities.Products.Where(p => histories.Contains(p.ID));
Contains
is the appropriate method to detect whether a value is within another collection. However, you may find it would be more appropriate to use a join here.
Also, I'm concerned about this query:
That doesn't represent the 5 most recently viewed histories - it represents "some arbitrary 5 view histories" (the first 5 returned in some indeterminate order) then arranged in most-recent-first order.
I suspect you actually want:
var histories = _entities.ProductViewHistories.OrderByDescending(p=>p.DateViewed)
.Take(5);
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