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Create a Tuple in a Linq Select
(6 answers)
Closed 6 years ago.
I have 2 database tables.
In Table1 Calculate I have 1 row which is mapped via an Id to multiple rows in table2 CalculdateData.
Now I need to load the data from table1 Calculate with all relevant Details from Table2 CalculdateData.
How would i have the Details into a Tuple-List.?
So basically for CalculateData I have 4 columns per row which I Need to put into a Tuple. Meaning if I would have for example 4 rows i need to create 4 Tuples in a List.
IEnumerable<Storage> context = new MyEntities();
var Result = (from a in context.calculate
join b in context.CalculateData on a.Id equals b.CalcId into c
where a.SpecialID == 2023 && a.VersionId == 1
orderby a.InternalOrderNr ascending
select new Storage
{
myField1 = a.Field1;
myField2 = a.Field2;
myField3 = a.Field3;
< MISSING PART AND QUESTION >
}).ToList();
return Result;
public class Storage
{
public int myField1;
public int myField2;
public int myField3;
public List<Tuple<int, int, string, decimal>> myField4;
}
This should work:
var Result = (from a in calculate
join b in calculateData on a.Id equals b.CalcId into c
where a.SpecialID == 2023 && a.VersionId == 1
orderby a.InternalOrderNr ascending
select new Storage
{
myField1 = a.Field1,
myField2 = a.Field2,
myField3 = a.Field3,
myField4 = c.Select(d => new Tuple<int, int, string, decimal>
(d.Field1, d.Field2, d.Field3, d.Field4))
.ToList()
}).ToList();
return Result;
It also would be good thing to check that this query transforms in single sql request and you not making new sql request on each tuple list creation.
Edit: In case you will have problems with custom types in query (as #Toxantron pointed) this selection should work:
var queryResult = (from a in calculate
join b in calculateData on a.Id equals b.CalcId into c
where a.SpecialID == 2023 && a.VersionId == 1
orderby a.InternalOrderNr ascending
select new
{
a.Field1,
a.Field2,
a.Field3,
myField4 = c.Select(d => new {
d.Field1, d.Field2, d.Field3, d.Field4})
}).ToList();
result = queryResult.Select(r => new Storage
{
myField1 = r.Field1,
myField2 = r.Field2,
myField3 = r.Field3,
myField4 = r.myField4.Select(t => new Tuple<int,int,decimal,string>
(t.Field1, t.Field2, t.Field3, t.Field4))
.ToList()
})
return Result;
You could try something like this.This is not tested yet.
select new Storage
{
myField1 = a.Field1,
myField2 = a.Field2,
myField3 = a.Field3,
myField4 = c.Select(d => new Tuple<int, int, string, decimal>(d.Field1, d.Field2, d.Field3, d.Field4)).ToList()
}).ToList();
This is totally based on this This tutorial
Related
im required to make a query to db to fetch data fro a highchart widget in our site here is the code I use currently,
var highChartsData =
(from a in db.roomdetails
join b in db.ApplySchedule on a.RoomId equals b.RoomID
where b.Status == true
select new HighlinePie
{
Title = a.RoomName,
Date = b.MDate,
Value = db.ApplySchedule.Where(x => x.RoomID == a.RoomId).GroupBy(x=>x.MDate).Count(),
}).ToList();
The problem with this approach is right now get the total count but what i need is the count based on date, for example if there was two entry on date 12/09/20201 and three entry on 14/09/20201 the data should be "Title,12/09/20201,2","Title,14/09/20201,3".
You have to use grouping:
var groupQuery =
from a in db.roomdetails
join b in db.ApplySchedule on a.RoomId equals b.RoomID
where b.Status == true
group b by new { a.RoomName, b.MDate } into g
select new HighlinePie
{
Title = g.Key.RoomName,
Date = g.Key.MDate,
Value = g.Count()
};
var highChartsData = groupQuery.ToList();
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();
I have the following SQL that I would like to write as a single linq statement:
SELECT
P.PartyId,
P.PartyDate,
SUM(COALESCE(R.PaidAmount, 0)) AS AmountPaid
FROM
Party AS P
LEFT JOIN Reservation as R
ON P.PartyID = R.PartyID
GROUP BY P.PartyID, P.PartyDate
ORDER BY P.PartyDate DESC
The best I can do is use two sets of linq queries, like so:
var localList = from partyList in localDb.Parties
join reservationList in localDb.Reservations on
partyList.PartyID equals reservationList.PartyID into comboList
from newList in comboList.DefaultIfEmpty()
select new PartyAmounts {
PartyID = partyList.PartyID,
PartyDate = partyList.PartyDate,
AmountPaid = (newList.PaidAmount ?? 0) };
var secondList = from groupList in localList
group groupList by new {
groupList.PartyID,
groupList.PartyDate} into resList
select new PartyAmounts {
PartyID = resList.Key.PartyID,
PartyDate=resList.Key.PartyDate,
AmountPaid = resList.Sum(x => x.AmountPaid)};
I don't care if it's a method chain or a lambda but I would love to know how this is supposed to go together. I can only barely understand the two I've got now.
Thanks for the help.
var list = from partyList in localDb.Parties
join reservationList in localDb.Reservations on partyList.PartyID equals reservationList.PartyID into comboList
from details in comboList.DefaultIfEmpty() // Left join
group details by new {partyList.PartyID, partyList.PartyDate} into grouped // So that the group have both keys and all items in details
select new PartyAmounts
{
PartyID = grouped.Key.PartyID,
PartyDate = grouped.Key.PartyDate,
AmountPaid = grouped.Sum(x => x.AmountPaid ?? 0)}
};
Hi i have the following code to select data from one table not in other table
var result1 = (from e in db.Users
select e).ToList();
var result2 = (from e in db.Fi
select e).ToList();
List<string> listString = (from e in result1
where !(from m in result2
select m.UserID).Contains(e.UserID)
select e.UserName).ToList();
ViewBag.ddlUserId = listString;
Am getting value inside listString .But got error while adding listString to viewbag.
Unable to cast object of type 'System.Collections.Generic.List`1[System.String]' to type 'System.Collections.Generic.IEnumerable`1[Main.Models.Admin.User]'.
First, could you update your question with the entire method so that we can see what might be going on with the ViewBag? Because your code should work just fine, assigning whatever value to the ViewBag is no problem normally:
ViewBag.property1 = 0;
ViewBag.property1 = "zero";
works just fine. ViewBag is dynamic. Now, you could get that error if you would later try to assing ViewBag.ddlUserId to something that actually is the wrong type.
I would like you to rewrite your statement as well, let me explain why. Assume for a moment that you have a lot ( > 100.000) of User records in your db.Users and we assume the same for Fi as well. In your code, result1 and result2 are now two lists, one containing >100.000 User objects and the other >100.000 Fi objects. Then these two lists are compared to each other to produce a list of strings. Now imagine the resource required for your web server to process this. Under the assumption that your actually using/accessing a separate SQL server to retrieve your data from, it would be a lot better and faster to let that server do the work, i.e. producing the list of UserID's.
For that you'd either use Kirill Bestemyanov's answer or the following:
var list = (from user in db.Users
where !db.Fi.Any(f => f.UserID == user.UserID)
select user.UserName).ToList()
This will produce just one query for the SQL server to execute:
SELECT
[Extent1].[UserName] AS [UserName]
FROM [dbo].[Users] AS [Extent1]
WHERE NOT EXISTS (SELECT
1 AS [C1]
FROM [dbo].[Fi] AS [Extent2]
WHERE [Extent2].[UserID] = [Extent1].[UserID]
)}
which in the end is what you want...
Just to clarify more:
var list = (from user in db.Users
where !db.Fi.Any(f => f.UserID == user.UserID)
select user.UserName).ToList()
can be written as the following lambda expression as well:
var list = db.Users.Where(user => !db.Fi.Any(f => f.UserID == user.UserID))
.Select(user => user.UserName).ToList()
which from the looks of it is slightly different from Kirill Bestemyanov's answer (which I slightly modified, just to make it look more similar):
var list = db.Users.Where(user => !db.Fi.Select(f => f.UserID)
.Contains(user.UserID))
.Select(user => user.UserName).ToList();
But, they will in fact produce the same SQL Statement, thus the same list.
I will rewrite it to linq extension methods:
List<string> listString = db.Users.Where(e=>!db.Fi.Select(m=>m.UserID)
.Contains(e.UserID))
.Select(e=>e.UserName).ToList();
try it, it should work.
Try this it is very simple.
var result=(from e in db.Users
select e.UserID).Except(from m in db.Fi
select m.UserID).ToList();
var res = db.tbl_Ware.where(a => a.tbl_Buy.Where(c => c.tbl_Ware.Title.Contains(mtrTxtWareTitle.Text)).Select(b => b.Ware_ID).Contains(a.ID));
This mean in T-SQL is:
SELECT * FROM tbl_Ware WHERE id IN (SELECT ware_ID, tbl_Buy WHErE tbl_Ware.title LIKE '% mtrTxtwareTitle.Text %')
getdata = (from obj in db.TblManageBranches
join objcountr in db.TblManageCountries on obj.Country equals objcountr.iCountryId.ToString() into objcount
from objcountry in objcount.DefaultIfEmpty()
where obj.IsActive == true
select new BranchDetails
{
iBranchId = obj.iBranchId,
vBranchName = obj.vBranchName,
Addressline1 = obj.Addressline1,
Adminemailid = obj.Adminemailid,
BranchType = obj.BranchType,
Country = objcountry.vCountryName,
CreatedBy = obj.CreatedBy,
CreatedDate = obj.CreatedDate,
iArea = obj.iArea,
iCity = obj.iCity,
Infoemailid = obj.Infoemailid,
Landlineno = obj.Landlineno,
Mobileno = obj.Mobileno,
iState = obj.iState,
Pincode = obj.Pincode,
Processemailid = obj.Processemailid,
objbranchbankdetails = (from objb in db.TblBranchesBankDetails.Where(x => x.IsActive == true && x.iBranchId == obj.iBranchId)
select new ManageBranchBankDetails
{
iBranchId = objb.iBranchId,
iAccountName = objb.iAccountName,
iAccountNo = objb.iAccountNo,
iBankName = objb.iBankName,
iAccountType = objb.iAccountType,
IFSCCode = objb.IFSCCode,
SWIFTCode = objb.SWIFTCode,
CreatedDate = objb.CreatedDate,
Id = objb.Id
}).FirstOrDefault(),
objbranchcontactperson = (from objc in db.tblbranchcontactpersons.Where(x => x.Isactive == true && x.branchid == obj.iBranchId)
select new ManageBranchContactPerson
{
branchid = objc.branchid,
createdate = objc.createdate,
Id = objc.Id,
iemailid = objc.iemailid,
ifirstname = objc.ifirstname,
ilandlineno = objc.ilandlineno,
ilastname = objc.ilastname,
imobileno = objc.imobileno,
title = objc.title,
updateddate=objc.updateddate,
}).ToList(),
}).OrderByDescending(x => x.iBranchId).ToList();
getdata = (from obj in db.TblManageBranches join objcountr in db.TblManageCountries on obj.Country equals objcountr.iCountryId.ToString() into objcount from objcountry in objcount.DefaultIfEmpty() where obj.IsActive == true
select new BranchDetails
{
iBranchId = obj.iBranchId,
vBranchName = obj.vBranchName,
objbranchbankdetails = (from objb in db.TblBranchesBankDetails.Where(x => x.IsActive == true && x.iBranchId == obj.iBranchId)
select new ManageBranchBankDetails
{
iBranchId = objb.iBranchId,
iAccountName = objb.iAccountName,
}).FirstOrDefault(),
objbranchcontactperson = (from objc in db.tblbranchcontactpersons.Where(x => x.Isactive == true && x.branchid == obj.iBranchId)
select new ManageBranchContactPerson
{
branchid = objc.branchid,
createdate = objc.createdate,
Id = objc.Id,
iemailid = objc.iemailid,
}).ToList(),
}).OrderByDescending(x => x.iBranchId).ToList();
I have a long list with ships that I get from a Linq to SQL query, but I only want one row per ImoNo. Today i have about 4 rows per ImoNo. I just need the one row that has been last updated (so in this example I need 2013-01-27).
This is my Linq To SQL query:
var res = from positions in context.Lloyds_ETAs
join vessels in context.Lloyds_Vessels on positions.ImoNumber equals vessels.imo_no
select new PositionData {
ImoNo = positions.ImoNumber,
PositionCordinates = positions.AIS_Latest_Position,
CompassOverGround = positions.Compass_over_Ground_Heading,
VesselId = positions.Vessel_ID,
Equipment = vessels.vessel_type,
Updated = positions.Last_Place_Location
};
return res.ToList();
var res = (from positions in context.Lloyds_ETAs
join vessels in context.Lloyds_Vessels on positions.ImoNumber equals vessels.imo_no
select new PositionData {
ImoNo = positions.ImoNumber,
PositionCordinates = positions.AIS_Latest_Position,
CompassOverGround = positions.Compass_over_Ground_Heading,
VesselId = positions.Vessel_ID,
Equipment = vessels.vessel_type,
Updated = positions.Last_Place_Location
})
.GroupBy(x => x.ImoNo)
.Select(g => g.OrderByDescending(pd => pd.Updated).First());
If you want the last one, all you have to do is append .OrderBy(pd => pd.Updated).Last() after your select.
var res = (from positions in context.Lloyds_ETAs
join vessels in context.Lloyds_Vessels on positions.ImoNumber equals vessels.imo_no
select new PositionData {
ImoNo = positions.ImoNumber,
PositionCordinates = positions.AIS_Latest_Position,
CompassOverGround = positions.Compass_over_Ground_Heading,
VesselId = positions.Vessel_ID,
Equipment = vessels.vessel_type,
Updated = positions.Last_Place_Location
}).OrderBy(pd => pd.Updated).Last();
return res.ToList();
(yourQuery).OrderByDescending(pd=>pd.Updated).First()
There are several ways to get just one "row" as a result:
res.OrderByDescending(x => x.Updated).Take(1);
res.OrderByDescending(x => x.Updated).First();
res.Order(x => x.Updated).Last();
It seems that you have some duplication though, so maybe doing a group by would be more appropriate.