Develop Reference

Why can't I select data from my LINQ sub query join?

I am trying to get data from 2 tables using a left join to a nested query. This allows me to get data from Item table but not the cart(nested query) table:
var q = from s in db.Items
join sub in (from c in db.Carts
where c.CartID == 1
group c by c.ItemID into g
select new
{
ItemID = g.Key,
Qty = g.Select(s => s.Qty)
}) on s.ItemID equals sub.ItemID into a
select new ItemViewModel
{
CategoryID = s.CategoryID,
Description = s.Description,
Price = s.Price,
**This being the issue------>>>>>>>** //Qty = a.Select(j => j.Qty),
ItemID = s.ItemID,
ItemName = s.ItemName
};
viewModel = q.ToList();
The query i am trying to acheive is:
select Items.*, Cart.Qty
from Items
left join (select ItemID, Qty from carts where CartID = 1 ) Cart
on Items.ItemID = Cart.ItemID

You can use GroupJoin with SelectMany for LEFT JOIN SQL Query and get the desired output.
var result = db.Items.GroupJoin(db.Carts.Where(x => x.CartID == 1), item => item.ItemID, cart => cart.ItemID,
(item, cart) => new { item, cart })
.SelectMany(x => x.cart.DefaultIfEmpty(), (it, ca) =>
{
return new ItemViewModel
{
ItemName = it.item.ItemName,
Price = it.item.Price,
ItemID = it.item.ItemID,
// ... .... ....
// Fill the required columns from it.Item property..
Qty = ca != null ? ca.Qty : 0
};
}).ToList();
EDIT: The LINQ version with SelectMany.
var result = from s in db.Items
join sub in (from c in db.Carts
where c.CartID == 1
select c)
on s.ItemID equals sub.ItemID into joined
from row in joined.DefaultIfEmpty()
select new ItemViewModel
{
CategoryID = s.CategoryID,
Description = s.Description,
Price = s.Price,
Qty = row != null ? row.Qty : 0,
ItemID = s.ItemID,
ItemName = s.ItemName
};
The C# Fiddle with sample data.

If I'm understanding correctly, and assuming that ItemViewModel.Qty property is just an int, the simplest form of the query you want is:
var q = from item in items
join cart in
(from cart in carts where cart.CartID == 1 select cart)
on item.ItemID equals cart.ItemID into itemCarts
select new ItemViewModel
{
ItemID = item.ItemID,
Qty = itemCarts.Sum(cart => cart.Qty)
};
If you want to only slightly modify/fix your query:
var q = from s in db.Items
join sub in (from c in db.Carts
where c.CartID == 1
group c by c.ItemID into g
select new
{
ItemID = g.Key,
Qty = g.Sum(s => s.Qty)
// or Qty = g.Select(s => s.Qty)
// and below: Qty = a.SelectMany(x => x.Qty).Sum()
})
on s.ItemID equals sub.ItemID into a
select new ItemViewModel
{
CategoryID = s.CategoryID,
Description = s.Description,
Price = s.Price,
Qty = a.Sum(x => x.Qty),
ItemID = s.ItemID,
ItemName = s.ItemName
};

LINQ: Multiple Join With Max Revision Filter

So I have this line:
var transrevmax = db.TRANSACTs
.Where(x => x.SITE == "1" &&
x.DATE_IN >= dateinchoice &&
x.DATE_OUT <= dateoutchoice)
.GroupBy(x => x.TICKET_NO)
.Select(x => x.OrderByDescending(y => y.REV_NO).FirstOrDefault())
.ToList();
and it returns the exact list of transactions I want the join below to go through to obtain values from...
var exportrecovery = (from trans in transrevmax
join detail in db.DETAILs on new { TICKET_NO = trans.TICKET_NO, REV_NO = trans.REV_NO } equals new { TICKET_NO = detail.TICKET_NO, REV_NO = detail.REV_NO }
join job in db.JOBs on new { JOB_CODE = trans.JOB_CODE, CUST_CODE = trans.CUST_CODE } equals new { JOB_CODE = job.CODE, CUST_CODE = job.CUST_CODE }
join customer in db.CUSTOMERs on trans.CUST_CODE equals customer.CODE
join invoiced in db.INVOICEDs on trans.TICKET_NO equals invoiced.TICKET_NO
where trans.DATE_IN >= dateinchoice && trans.DATE_OUT <= dateoutchoice && trans.STATUS.ToString().Trim() != "V" && trans.STATUS.ToString().Trim() != "E"
select new { ADDRESS = customer.ADDRESS, CITY = customer.CITY, STATE = customer.STATE, ZIP = customer.ZIP, FREIGHT = detail.HAUL_CHGE + detail.FUEL_CHGE, JOB_NAME = job.NAME, HAUL_TAX = detail.HAUL_TAX, INVOICE_NO = invoiced.INVOICE_NO, CUST_NAME = customer.NAME, TAX_CODE = customer.TAX_CODE, MAT_CHGE = detail.MAT_CHGE, MAT_TAX = detail.MAT_TAX, MAT_CODE = detail.MAT_CODE, QTY = detail.QTY, PRICE = detail.PRICE, DATE_MOD = trans.DATE_OUT, REV_NO = trans.REV_NO, SITE = trans.SITE, TICKET_NO = trans.TICKET_NO, CUST_CODE = trans.CUST_CODE, JOB_CODE = trans.JOB_CODE }
).ToList();
... if I run the first line I get the transactions limited to only those with the max revision (what I want), and if I run the join (replacing the "transrevmax" with the table "db.TRANSACTs") I get the right range of ticket numbers, but it includes all revisions. I am stumped as to how I can use the joined tables and get only unique rows according to their (maximum) revision number. When these two are used in conjunction I receive zero rows. Please advise.

Remove the ToList on the transrevmax creation.

How to get the group sum in my complex linq query

below I have listed a linq query that works properly in my asp.net.mvc web app.
In addition I would like to group over 'allowance.ParameterId' in order to get the group sum for 'allowance.Freight (instead of multiple records for the given key).
var query = from ara in aras
join company in companies on ara.Id equals company.ARAId
join wasteWater in wasteWaters on company.Id equals wasteWater.CompanyId
join allowance in allowances on wasteWater.Id equals allowance.WasteWaterID
join parameter in parameters on allowance.ParameterId equals parameter.Id into JoinedParameterAllowance
from parameter in JoinedParameterAllowance.DefaultIfEmpty()
where company.Activ == true && company.End == null && company.Template == false
&& wasteWater.End == null
select new FreightSummaryViewModel
{
AraName = ara.Name,
AraId = ara.Id,
AllowedParameter = parameter.Name,
AllowedFreight = allowance.Freight
};
I have tried to insert 'group ...' but failed to get it right.
Could someone help me please to set up the proper syntax?
Thank you in advance, Manu

I have little idea about relations in your database, so I improvised...
// Some dummy data to play with
var aras = Enumerable.Range(0, 5).Select(i => new { Id = i, Name = "Ara" + i });
var companies = Enumerable.Range(0, 15).Select(i => new { Id = i, ARAId = i % 5, Activ = true, End = (DateTime?)null, Template = false });
var wasteWaters = Enumerable.Range(0, 35).Select(i => new { Id = i, CompanyId = i / 15, End = (DateTime?)null });
var allowances = Enumerable.Range(0, 70).Select(i => new { Id = i, WasteWaterID = i, ParameterId = i % 4, Freight = i * 1000 });
var parameters = Enumerable.Range(0, 4).Select(i => new { Id = i, Name = "Parameter" + i });
And this is what I believe you looked for:
var query =
from ara in aras
join company in companies on ara.Id equals company.ARAId
join wasteWater in wasteWaters on company.Id equals wasteWater.CompanyId
join allowance in allowances on wasteWater.Id equals allowance.WasteWaterID
join parameter in parameters on allowance.ParameterId equals parameter.Id
into JoinedParameterAllowance
// from parameter in JoinedParameterAllowance.DefaultIfEmpty()
where true
&& company.Activ == true
&& company.End == null
&& company.Template == false
&& wasteWater.End == null
group allowance by new
{
AraName = ara.Name,
AraId = ara.Id,
ParameterId = allowance.ParameterId
} into myGroup
select new //FreightSummaryViewModel
{
AraName = myGroup.Key.AraName,
AraId = myGroup.Key.AraId,
AllowedParameter = myGroup.Key.ParameterId,
AllowedFreight = myGroup.Sum(g => g.Freight)
};

join with multiple group by element and select extra columns

Can you please help to convert this from sql to linq, i am new to linq and been trying this and couldn't succeed. Let me know if this is even possible or not?
SELECT max(Products.ProductID) as ProductID, Products.SKU, Products.Name, Products.RRP, Products.Price,
max(Products.FrontTall) as FrontTall,
ProductsCategory.SortOrder,
Products.ColorValue,
max(Products.ColorImg) as ColorImg,
Products.IsPrimary,
Products.Visible
FROM Products INNER JOIN ProductsCategory ON Products.ProductID = ProductsCategory.ProductID
WHERE (ProductsCategory.CategoryID = 5 ) AND (Products.Visible = 1) AND (Products.Inactive = 0) AND (Products.Deleted = 0 or Products.Deleted is null)
GROUP BY SKU, Products.Name, RRP, Price, ColorValue, ProductsCategory.SortOrder, IsPrimary, Visible
AND this is what i am trying
var products = (from p in db.Products
join cp in db.ProductsCategories on p.ProductID equals cp.ProductID
where cp.CategoryID == catId && p.Visible == true && p.Inactive == false && (p.Deleted == null || p.Deleted == false)
group p by new {
p.SKU,
p.Name,
p.RRP,
p.Price,
p.ColorValue,
p.IsPrimary,
p.Visible,
cp.SortOrder
} into grouped
select new {
ProductID,
FrontTall,
ColorImg,
SKU = grouped.Key.SKU,
Name = grouped.Key.Name,
RRP = grouped.Key.RRP,
Price = grouped.Key.Price,
ColorValue = grouped.Key.ColorValue,
IsPrimary = grouped.Key.IsPrimary,
Visible = grouped.Key.Visible,
SortOrder = grouped.Key.SortOrder
})
.OrderBy(x => x.SortOrder);
I need to get the ProductID, FrontTall and ColorImg field value without including in group by
Thanks in advance.
Kish

select new {ProductID = grouped.Max(x => x.ProductID)}

How to write Outer Join using LINQ

I am using the below Inner Join to retrive the Data between the two tables, but all data is not getting populated. I tried implementing Outer join by connecting using CCY1== CCY1 and PCODE == PCODE, but no luck.
var q = from g1 in TableCCY1.AsEnumerable()
join g2 in TableCCY2.AsEnumerable()
on g1.Field<string>("CCY1") equals g2.Field<string>("CCY1")
where g1.Field<string>("PCODE") == g2.Field<string>("PCODE")
select new
{
g1currency = g1.Field<string>("CCY1"),
g2currency = g2.Field<string>("CCY1"),
g1code = g1.Field<string>("PCODE"),
g2code = g2.Field<string>("PCODE"),
g1Amt1 = g1.Field<string>("AMT1"),
g2Amt2 = g2.Field<string>("AMT2")
};
Thanks for your help.

For left join you can use this approuch: http://msdn.microsoft.com/en-us/library/vstudio/bb397895.aspx
The code should be:
var q = from g1 in TableCCY1
join g2 in TableCCY2 on g1.CCY1 equals g2.CCY1 && g1.PCODE equals g2.PCODE into TableCCY3
from g3 in TableCCY3.DefaultIfEmpty()
select new
{
g1currency = g1.CCY1,
g2currency = (g3 == null ? String.Empty : g3.CCY1),
g1code = g1.PCODE,
g2code = (g3 == null ? String.Empty : g3.PCODE),
g1Amt1 = g1.AMT1,
g2Amt2 = (g3 == null ? 0 : g3.AMT2)
};

It looks like you just want to union/concat the two tables into one and then just group on those two columns. You're not logically joining the two tables. That actually makes it much easier.
var q = from row in TableCCY1.AsEnumerable().Concat(TableCCY2.AsEnumerable())
group row by new
{
CCY1 = row.Field<string>("CCY1"),
PCode = row.Field<string>("PCODE")
} into matches
select new
{
CCY1 = matches.Key.CCY1,
PCODE = matches.Key.PCode,
Sum = matches.Sum(match => match.Field<decimal?>("AMT2")),
};