Converting a summed sql query to LINQ - linq-to-sql

Question

I have the following SQL code from a legacy application that I have been given to work on:
SELECT [timePeriodLabel]
,[tariffCost]
,[totalUnits]
,[totalMoneyValue]
into #allRates
FROM [halfHourlyCustomers3NF].[dbo].[halfHourlyBillsTariffTotals]
where invoiceNumber = #invoiceNumber
select 'eveningAndWeekend' as timePeriodLabel,
tariffcost,
sum(totalUnits) as totalUnits,
sum(totalMoneyValue) as totalMoneyValue
into #newCollection
from #allRates
where timePeriodLabel = 'evening' or
timePeriodLabel = 'weekend'
group by tariffcost
insert into #newCollection
select 'winterDay' as timePeriodLabel,
tariffcost,
sum(totalUnits) as totalUnits,
sum(totalMoneyValue) as totalMoneyValue
from #allRates
where timePeriodLabel = 'winterDayBeforePeak' or
timePeriodLabel = 'winterDayAfterPeak'
group by tariffcost
insert into #newCollection
select 'night' as timePeriodLabel,
tariffcost as tariffCost,
sum(totalUnits) as totalUnits,
sum(totalMoneyValue) as totalMoneyValue
from #allRates
where timePeriodLabel = 'nightWeekday' or
timePeriodLabel = 'morningWeekday' or
timePeriodLabel = 'nightWeekend' or
timePeriodLabel = 'morningWeekend'
group by tariffcost
insert into #newCollection
select *
from #allRates
where not(timePeriodLabel = 'winterDayBeforePeak' or
timePeriodLabel = 'winterDayAfterPeak' or
timePeriodLabel = 'nightWeekday' or
timePeriodLabel = 'morningWeekday' or
timePeriodLabel = 'nightWeekend' or
timePeriodLabel = 'morningWeekend'or
timePeriodLabel = 'evening' or
timePeriodLabel = 'weekend')
select *
from #newCollection
This helps to filter and sum data from a table as follows:
winterDayBeforePeak 12.0000 926.5850 111.1900
winterDayAfterPeak 12.0000 151.7650 18.2100
winterPeak 13.0000 331.5100 43.1000
evening 6.0000 172.9250 10.3800
weekend 6.0000 616.5350 36.9900
nightWeekday 8.0000 1362.5150 109.0000
morningWeekday 8.0000 3627.2750 290.1800
nightWeekend 8.0000 533.8800 42.7100
morningWeekend 8.0000 1439.3100 115.1400
I have created an Entity framework application with a List variable called TariffTotals and I want to add the results of the query transformation into another List variable called SummerTariffTotals
I have looked on MDSN for the documentation to do this and I came across this article:[EF Summing Link][1]
Having looked at some answers on Stack Overflow I have tried the following:
var test = db.TariffCaclulations.GroupBy(row => new { row.TariffCost })
.Select(g => new HalfHourlyBillTariffCalculation()
{
TimePeriodLabel = "eveningAndWeekend",
TariffCost = g.Key.TariffCost,
TotalUnits = g.Sum(x => x.TotalUnits),
TotalMoneyValue = g.Sum(x => x.TotalMoneyValue)
})
.ToList();
Once I have the variable I was then going to add it to the summed table but I am getting an error The entity or complex type 'Project.Models.HalfHourlyBillTariffCalculation' cannot be constructed in a LINQ to Entities query."}
Any pointers on how I can overcome this?

Answer 1

The error tells you that you can't create complex type. That means you can't create new Entity object from your linq query. You should create POCO object and everything should be fine:
Your POCO class:
public class HalfHourlyBillTariffCalculationPOCO
{
public string TimePeriodLabel { get; set; }
public decimal TariffCost { get; set; }
public decimal TotalUnits { get; set; }
public decimal TotalMoneyValue { get; set; }
}
Then your cal use it easily:
var test = db.TariffCaclulations.GroupBy(row => new { row.TariffCost })
.Select(g => new HalfHourlyBillTariffCalculationPOCO()
{
TimePeriodLabel = "eveningAndWeekend",
TariffCost = g.Key.TariffCost,
TotalUnits = g.Sum(x => x.TotalUnits),
TotalMoneyValue = g.Sum(x => x.TotalMoneyValue)
})
.ToList();