linq - 尝试将交叉连接 transact-sql 转换为 LINQ

Question

我正在尝试解决这个交叉连接(我以前从未见过的东西)，以便我可以转换为 LINQ。我不确定它要做什么:

Select various a,b,c,d, and e columns
From Fee a
inner Join FeeCategory b on a.CategoryID = b.FeeCategoryID
inner join FeeCompanyType c on a.FeeID = c.FeeID
cross join FeeType e
left outer join FeeTypeLink d on a.FeeID = d.FeeID and e.FeeTypeID = d.FeeTypeID

到

var q = (
    from fees in Session.Query<Fee>()
    join feeCategories in Session.Query<FeeCategory>() on fees.FeeCategory.Id equals feeCategories.Id
    join feeCompanyType in Session.Query<FeeCompanyType>() on fees.Id equals feeCompanyType.Fee.Id
**erm.....**
)

大脑崩溃，任何帮助表示赞赏......

Answer 1

对于交叉连接，只需添加另一个 from :

from fees in Session.Query<Fee>()
//cross join:
from feetypes in Session.Query<Session.Query<Fee>()
join ...
join ...
// left join:
join feetypelink in Session.Query<FeeTypeLink>() on 
new {fees.FeeID,feetypes.FeeTypeID} equals new{feetypelink.FeeID,feetypelink.FeeTypeID} 
into gr
from res in gr.DefaultIfEmpty() .....