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我有这个查询，我试图把它作为 linq：

select * 
from stuff
inner join stuffowner so on so.stuffID = stuff.stuffID
left outer join (select  min(loanId) as loanId, stuffownerId from loan  
 where userid = 1 and status <> 2 group by stuffownerId) t on t.stuffownerid = so.stuffownerid
left outer join loan on t.LoanId = loan.LoanId

完成后，我想做一个 linq Group by 让 Stuff 拥有密钥，然后将 stuffowners + Loan 作为价值。

如果没有子查询，我似乎无法得到一个很好的查询（因此是双左外）。

所以基本上我的查询所做的是，对于我在数据库中的每个东西，带上所有者，然后我想带上用户在这些东西上所做的第一笔贷款。

我尝试了各种 linq：

from stuff in Stuffs
join so in StuffOwners on stuff.StuffId equals so.StuffId
join  tLoan in Loans on so.StuffOwnerId equals tLoan.StuffOwnerId into tmpJoin 
from tTmpJoin in tmpJoin.DefaultIfEmpty()
group tTmpJoin by new {stuff}  into grouped
select new {grouped, fluk = (int?)grouped.Max(w=> w.Status )}

这不好，因为如果我没有得到东西所有者，最重要的是它似乎会产生很多查询（LinqPad）

from stuff in Stuffs
join so in StuffOwners on stuff.StuffId equals so.StuffId
join tmpLoan in 
 (from tLoan in Loans group tLoan by  tLoan.StuffOwnerId into g 
 select new {StuffOwnerId = g.Key, loanid = (from t2 in g select t2.LoanId).Max()})
 on so.StuffOwnerId equals tmpLoan.StuffOwnerId
 into tmptmp  from tMaxLoan in tmptmp.DefaultIfEmpty()
select new {stuff, so, tmptmp}

似乎也产生了很多子查询。

我试过 let keyworkd ：

from  tstuffOwner in StuffOwners 
let tloan = Loans.Where(p2 => tstuffOwner.StuffOwnerId == p2.StuffOwnerId).FirstOrDefault()
select new { qsdq = tstuffOwner, qsdsq= (int?) tloan.Status, kwk= (int?) tloan.UserId, kiwk=  tloan.ReturnDate  }

但我从 tLoan 获得的信息越多，查询越长，子查询越多

实现这一目标的最佳方法是什么？谢谢

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0 回答 0