How can I use this Linq Query using it with a multiple parameter by Join tables

Question

var list = dc.Orders.
            Join(dc.Order_Details,
            o => o.OrderID, od => od.OrderID, <-- what if i have 2 more parameters let say an ID and a REC on both table. ex.: o=> o.OrderID && o.ItemName, od => od.OrderID && od.Itemname then (o, od) but its result is error? is there another way?
            (o, od) => new
            {
                OrderID = o.OrderID,
                OrderDate = o.OrderDate,
                ShipName = o.ShipName,
                Quantity = od.Quantity,
                UnitPrice = od.UnitPrice,
                ProductID = od.ProductID
            }).Join(dc.Products,
                    a => a.ProductID, p => p.ProductID, <-- at this point too?
                    (a, p) => new
                    {
                        OrderID = a.OrderID,
                        OrderDate = a.OrderDate,
                        ShipName = a.ShipName,
                        Quantity = a.Quantity,
                        UnitPrice = a.UnitPrice,
                        ProductName = p.ProductName
                    });

is it possible to use this lambda expression linq query with multiple parameters by joining 3 tables?

--- UPDATE STILL ERROR -- :(

var header = DB.Delivery_HeaderRECs.Join(DB.Delivery_DetailsRECs, <-- Red Line on DB.Delivery_HeaderRECs.Join
                                q => new { q.drNO, q.RecNO },
                                qw => new { qw.DrNO, qw.RecNO },
                                (q, qw) => new
                                {
                                    DR = q.drNO,
                                    DATE = q.DocDate,
                                    RECNO = q.RecNO,
                                    CUSTID = q.CustomerID,
                                    CUSTADDR = q.CustomerADDR,
                                    RELEASE = q.ReleasedBy,
                                    RECEIVE = q.ReceivedBy,
                                    REMARKS = q.Remarks,

                                    ITEM = qw.ItemCode,
                                    DESC = qw.ItemDesc,
                                    QTY = qw.Qty,
                                    COST = qw.Unit,
                                    PLATENO = qw.PlateNo,
                                    TICKETNO = qw.TicketNo
                                }).Join(DB.Delivery_TruckScaleRECs,
                                w => new { w.DR, w.TICKETNO },
                                we => new { we.DrNo, we.TicketNO },
                                (w, we) => new 
                                {
                                    DR = w.DR,
                                    DATE = w.DATE,
                                    RECNO = w.RECNO,
                                    CUSTID = w.CUSTID,
                                    CUSTADDR = w.CUSTADDR,
                                    RELEASE = w.RELEASE,
                                    RECEIVE = w.RECEIVE,
                                    REMARKS = w.REMARKS,

                                    ITEM = w.ITEM,
                                    DESC = w.DESC,
                                    QTY = w.QTY,
                                    COST = w.COST,
                                    PLATENO = w.PLATENO,
                                    TICKETNO = w.TICKETNO,

                                    TRANSAC = we.TransactionType,
                                    FWEIGHT = we.FirstWeight,
                                    SWEIGHT = we.SecondWeight,
                                    NWEIGHT = we.NetWeight
                                }).FirstOrDefault();

I made up changes base on the answer but an error said above the statement: "The type arguments for method cannot be inferred from the usage. Try specifying the type arguments explicitly". i think it's talking about the parameters i've made..

What do you mean by not on both table? looks like those 2 parameters are some kind of outside variables? — King King
– King King, Commented Nov 23, 2013 at 2:47

King King · Accepted Answer · 2013-11-23 03:35:27Z

1

You can use anonymous type for the Join like this:

var list = dc.Orders.Join(dc.Order_Details,
                          o => new { o.OrderID, o.ItemName}, 
                          od => new { od.OrderID, od.ItemName},
                          ...);

The anonymous type will be compiled to use the autoimplemented Equals and GetHashCode so that the equality will be derived by the equality of all the corresponding properties. Just add more properties as you want in the the new {....}. Note that the order of properties provided in the 2 new {...} should be the same order of correspondence. The names should also be matched, you can explicitly specify the names to ensure this (this is needed in some cases) such as:

new {OrderID = o.OrderID, Name = o.ItemName}

However in your case the property names will be used as the same properties of the item.

UPDATE

This update is just a fix for your specific parameters, I said that the property names should be the same, if they are not you have to explicitly name them like this:

var list = dc.Orders.Join(dc.Order_Details,
                           q => new {DrNO =  q.drNO, q.RecNO}, 
                           qw => new {DrNO = qw.DrNO, qw.RecNO},
                           ...);

edited Nov 23, 2013 at 3:35

answered Nov 23, 2013 at 3:00

King King

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8 Comments

Oblivious7 Over a year ago

it has an error sir... i'll paste the whole code it says "the type arguments for method cannot be inferred from the usage try specifying the type arguments explicitly"

King King Over a year ago

@Oblivious7 could you post the whole code you tried? I'm sure there should not any error, BTW the ... is what you have to fill yourself. your o and od of course should have ItemName, it's just an example.

Oblivious7 Over a year ago

i update already the codes sir.. you can check it above i put a label at it updated error..

King King Over a year ago

@Oblivious7 please confirm this q.drNO, is that what you have or it's q.DrNO? Note that case-sensitivity is regarded. BTW, pleas re-read my answer, the corresponding property names should be the same

Oblivious7 Over a year ago

does it matter if on my Table 1 its drNO and in Table 2 its DrNO? must it suppose to be the same format?

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