没有加入Linq

Question

我在这样的查询中加入了两个表

IQueryable<Auction> closed =
                (from a in CurrentDataSource.Auctions
                 join p in CurrentDataSource.Payments
                     on a.Id equals p.AuctionId
                 where <some condition>
                 select a);

我真正想要的是说给我所有的拍卖，其中 IS NO 加入Payments表或某些条件为真。我可以用T-SQL做到这一点，但不知道如何用Linq做到这一点。你能帮忙吗？

Answer 1

您可以使用左外连接并检查付款是否为空，就像在T-SQL中一样。

IQueryable<Auction> closed =
                (from a in CurrentDataSource.Auctions
                 join p in CurrentDataSource.Payments
                     on a.Id equals p.AuctionId into temp
                 from t in temp.DefaultIfEmpty()
                 where t == null && <some condition>
                 select a);