加入所有的子表一起，搶到第一個

Question

我希望能拉包含產品的最後一個發票的類別 類別 - >產品展示 - >發票

(from p as Product in cat 
where p.InvoiceList.Where(function(o) o.InvoiceDate >= MAX_ONE) 
select p.InvoiceList.Where(function(o) o.InvoiceDate >= MAX_ONE) 
).FirstOrDefault() 

我好像不太可能包裝我的頭如何做到這一點。

編輯：將實現我的目標的示例SQL語句。如果我只能把它翻譯...

SELECT TOP 1 i.InvoiceID, i.InvoiceDate, i.TotalAmount 
FROM   Category as c INNER JOIN 
        Product as p ON p.categoryID = c.categoryID INNER JOIN 
        InvoiceProducts as ip ON ip.productID = p.productID INNER JOIN 
        Invoice as i ON ip.InvoiceID = i.InvoiceID 
WHERE  c.categoryID = 3 
ORDER BY InvoiceDate DESC 

Answer 1

cat.SelectMany(p => p.InvoiceList).OrderBy(o => o.InvoiceDate).LastOrDefault(); 

Answer 2

var lastInvoice = (from i in context.Invoices 
    .where i.Product.CategoryId == categoryId 
    .select i) 
     .OrderByDescending(i=>i.IbvoiceDate) 
     .FirstOrDefault();