linq to sql中的嵌套IN子查询答案

【问题标题】：nested IN subquery in linq to sqllinq to sql中的嵌套IN子查询
【发布时间】：2015-06-17 11:14:30
【问题描述】：

困惑如何将这个 sql 查询写入 linq to sql

select FirstName from [User] where [UserId] in(

select LenderId from AffiliateLenderRelation where AffiliateId in (select Userid From [User] where [UserId] = 11)
)

到目前为止我已经尝试过什么

var innerquery = from iq in db.AffiliateLenderRelations where iq.AffiliateId == loggedInUser.UserId select iq.AffiliateId;
                List<SelectListItem> lenders = db.Users
                .Where(o => o.AccountTypeId == 1 && o.Deleted == false && innerquery.Contains(o.UserId))
                .Select(o => new SelectListItem()
                {
                    Value = o.UserId.ToString(),
                    Text = o.FirstName
                }).ToList();
                        lenders.Insert(0, new SelectListItem() { Value = "0", Text = "All" });

【问题讨论】：

标签： sql linq linq-to-sql

【解决方案1】：

您的代码中的一切都很好，我猜只有一个错误。

将选择 iq.AffiliateId 更改为 => iq.LenderId

var innerquery = from iq in db.AffiliateLenderRelations where iq.AffiliateId == loggedInUser.UserId select iq.AffiliateId;
                List<SelectListItem> lenders = db.Users
                .Where(o => o.AccountTypeId == 1 && o.Deleted == false && innerquery.Contains(o.UserId))
                .Select(o => new SelectListItem()
                {
                    Value = o.UserId.ToString(),
                    Text = o.FirstName
                }).ToList();
                        lenders.Insert(0, new SelectListItem() { Value = "0", Text = "All" });

【讨论】：

【解决方案2】：

我认为不需要嵌套查询。您可以使用连接查询。试试这个

var lobj= (from u db.Users.where(x=>x.UserId==11)
                                 let ces = from ce in db.AffiliateLenderRelation.where( y=> y.AccountTypeId == 1 && y.Deleted == false )
                                           select ce.LenderId 
                                 where ces.Contains(u.UserID)
                             .Select(o => new SelectListItem()
                    {
                        Value = o.UserId.ToString(),
                        Text = o.FirstName
                    })).ToList();

【讨论】：

我已经更新了我的问题，有一些变化，你能更新你的答案吗，我想以使用子查询为例。