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Convert sql query to linq in C#

Hi Could any one help how to write this below query in Linq C#
select YearValue from [Information].Year
where YearId in (select max(YearId) from curreny where BudgetCodeId = 2)
Here's what I've tried:
var maxYear =
from year in dbContext.Years
join exchange in dbContext.CurrencyExchangeRates
on year.YearId equals exchange.YearId
where exchange.BudgetCodeId == budgetCodeId
orderby year.YearValue descending
select new { yearValue = year.YearValue };

This is what you're looking for:
var maxYear = from year in dbContext.Years where (from exchange in dbContext.CurrencyExchangeRates where exchange.BudgetCodeId == 2 select exchange)
.Max(m => m.YearId) ==
year.YearId select year.YearValue;
int mYear = maxYear.First();

Converting SQL to linq with a right join (advanced)

I have the following SQL statement:
SELECT dh.*
FROM table1 w
LEFT OUTER JOIN table2 dh
on w.CBranch = dh.CBranch
AND w.CWorkstation = dh.CWorkstation
AND w.CNumber = dh.CNumber
RIGHT OUTER JOIN table3 dl
on dh.Id = dl.DispatchHeaderId
AND w.CLine = dl.CLine
AND w.CLineVersion = dl.CVersion
where w.ItemStatus = 9
AND dh.Shipping = 0
ORDER BY dh.CNumber ASC
I am beginner in Linq and not sure how to do advanced linq.
Could someone please guide me writing equivalent linq for this.
I am using C#, EF4.
I have managed to get till here, but not sure f this is correct.
var wos = scope.Context.table1.Where(
a => a.ItemStatus == (short)LineStatus.Packed)
.GroupBy(a => new { a.CNumber, a.CBranch, a.CWorkstation})
.Select(a => a.FirstOrDefault()).ToList();
var headerGroups = new List<IEnumerable<table2>>();
foreach(var status in wos)
{
if (status == null)
{
continue;
}
var headerList = scope.Context.table2s.Where(
b => b.CBranch == status.CBranch &&
b.CNumber == status.CNumber &&
b.CWorkstation == status.CWorkstation).ToList();
if (headerList != null && headerList.Any())
{
headerGroups.Add(headerList);
}
};

use defaultifemty() method in following link way....
http://smehrozalam.wordpress.com/2009/06/10/c-left-outer-joins-with-linq/

LINQ SELECT TAKE 1 EACH ROW

How can i select take 1 each data in column in linq that only return 1 row. Because when i put .Take(1) only 1 row result will appear but i want to have 2 row result with different entry
to make it clear here's what i mean
in c# here's my query
using (PharmacyDBEntities entities = new PharmacyDBEntities())
{
var positem = (from a in entities.POSEntries.Take(1)
where a.Invoice.AccountID == authLogin.userid && a.Invoice.InvoiceStatusID == 1
select new
{
a.Item.ItemCode,
a.Item.Name,
Quantity = (from b in entities.POSEntries where b.Invoice.AccountID == authLogin.userid && b.Invoice.InvoiceStatusID == 1 select b).Count(),
a.Item.SellingPrice
}).ToList();
gcItemList.DataSource = positem;
}
And the result
Is there any suggestion guys? will make big help to me. thanks

You can use Linq GroupBy
var positem = entities.POSEntries.Where( a=> a.Invoice.AccountID == authLogin.userid && a.Invoice.InvoiceStatusID == 1)
.GroupBy(x=>x.Item.ItemCode).Select(g=> new {
g.Key,
g.First().Item.Name,
Quantity = g.Count(),
g.First().Item.SellingPrice
}).ToList();

So, you want Distinct() instead of Take(1)? Something along these lines:
var positem = (from a in entities.POSEntries
where a.Invoice.AccountID == authLogin.userid && a.Invoice.InvoiceStatusID == 1
select new
{
a.Item.ItemCode,
a.Item.Name,
Quantity = (from b in entities.POSEntries where b.Invoice.AccountID == authLogin.userid && b.Invoice.InvoiceStatusID == 1 select b).Count(),
a.Item.SellingPrice
}).Distinct().ToList();

Take only returns first n elements. I think you need to try using the Distinct method.

how to use Linq " NOT IN"

I'm using Entity Framework
So I want to write a sql command using two tables - tblContractor and tbSiteByCont tables.
It looks like this in SQL
SELECT PKConID, Fname, Lname
FROM tblContractor
WHERE (PKConID NOT IN
(SELECT FKConID
FROM tbSiteByCont
WHERE (FKSiteID = 13)))
but I don't know how to write in Linq.
I tried like this
var query1 = from s in db.tblSiteByConts
where s.FKSiteID == id
select s.FKConID;
var query = from c in db.tblContractors
where c.PKConID != query1.Any()
select Contractor;
But this doesn't work.
So how should I write it? What is the procedure? I'm new to Linq.

var _result = from a in tblContractor
where !(from b in tbSiteByCont
where FKSiteID == 13
select b.FKConID)
.Contains(a.PKConID)
select a;
or
var siteLst = tbSiteByCont.Where(y => y.FKSiteID == 13)
.Select(x => x.FKConID);
var _result = tblContractor.Where(x => !siteLst.Contains(x.PKConID));

I'd use a HashSet, it ensures you only evaluate the sequence once.
var result = from p in tblContractor
let hasht = new HashSet<int>((from b in tbSiteByCont
where b.FKSiteID == 13
select b.PKConID).Distinct())
where !hasht.Contains(p.PKConID)
select p;

may this work too
var _result = from a in tblContractor
.Where(c => tbSiteByCont
.Count(sbc => sbc.FKSiteID == 13 && c.PKConID == sbc.FKConID) == 0)

linq groupby question

I have a table that has several columns: HarvestID, HarvestDate, UserID to mention the main ones.
For each date, there are going to be several HarvestID per day.
So far, I have the following linq query:
TheUserID and TheMonth are passed in as an int and a DateTime
var MyQuery = from h in MyDC.HarvestTable
where h.UserID == TheUserID
where h.HarvestDate.Month == TheMonth.Month
where h.HarvestDate.Year == TheMonth.Year
group h by h.HarvestDate.Day into TheDays
from d in TheDays
select new
{
TheDay = d.HarvestDate.Date,
TheDayCount = (from c in TheDay
select c.HarvestID).Count()
};
I'm looking to have the output be a list of counts per day. The query doesn't bug but the problem is that at the moment the query is not returning a unique row for each day. The grouping doesn't work and I'm not finding out why. What's wrong with this code?
Thanks.

It think your query should be
var MyQuery = from h in MyDC.HarvestTable
where h.UserID == TheUserID
where h.HarvestDate.Month == TheMonth.Month
where h.HarvestDate.Year == TheMonth.Year
group h by h.HarvestDate.Day into TheDays
select new
{
TheDay = TheDays.Key,
TheDayCount = TheDays.Count()
};
Here is a vry good refrence to above group by statement http://msdn.microsoft.com/en-us/vcsharp/aa336754.aspx#simple1

var MyQuery = from h in MyDC.HarvestTable
where h.UserID == TheUserID
&& h.HarvestDate.Month == TheMonth.Month
&& h.HarvestDate.Year == TheMonth.Year
group h by h.HarvestDate.Day into g
select new
{
TheDay = g.Key,
TheDayCount = g.Count()
};
This will not give you zeroes on the days where there is no data - but should give you a count where there is.
http://msdn.microsoft.com/en-us/vcsharp/aa336746 is my go-to page for LINQ examples.