Linq - 左连接的正确格式

Question

我是linq的新手......我想知道我做得对..

这是我的代码......

var result = from a in ctx.ItemReceipts
             join b in ctx.ItemReceiptStatusTypes on a.Status equals b.ItemReceiptStatusTypeID
             join c in ctx.PurchaseOrders on a.ReferenceID equals c.PurchaseOrderID
             into leftJoinItemReceipts 
             from d in leftJoinItemReceipts.DefaultIfEmpty()
             where a.ItemReceiptID.Equals(ItemReceiptID)
             select new
             {
                 CItemReceiptID = a.ItemReceiptID,
                 CTransactionNumber = a.TransactionNumber,
                 CRemarks = a.Remarks,
                 CStatus = a.Status,
                 CStatusType = b.Description,
                 CReferenceID = a.ReferenceID,
                 CReferenceTypeID = a.ReferenceTypeID,
                 CTransactionDate = a.TransactionDate,
                 CDateReceived = a.DateReceived,
                 CTotalCost = a.TotalCost,
                 CPONumber = d.PONumber                     
             };

它运行得很完美...但是我真的无法理解into部分..我不知道它是否真的是一个左连接而是给了我想要的数据...它给了我所有的数据itemreceipts即使他们与PurchaseOrder ....

没有共同点

我需要解释...更好的mysql和linq之间的比较...

Answer 1

skipOnEmpty

这将在ItemReceipts和ItemReceiptStatusTypes上进行左连接，然后使用PurchaseOrders进行内连接