How To Use Aggregate Function In LINQ
Nov 1, 2011
I want to get the average of this query.
From d In (From c In location.Descendants("temperature")
Where c.Attribute("type").Value = "hourly" Select c).Descendants("value")
Take 3
Select d
I can see the aggregate keyword in the autocomplete dropdown, but how to apply it.
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Feb 21, 2011
I want to Sum of the calculated column Red which is calculated in the Function IsRed() that return an integer.When I run the query I get the following error: Method 'Int32 IsRed(Int32)' has no supported translation to SQL.How should I rewrite this to get it to work.
[Code]...
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Apr 6, 2011
I've seen the operator Max used two different ways. The following two queries produce the same results. The MSIL code is slightly different. What is the benefit of using the Aggregate operator? Logically, is there a difference?
[Code]...
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May 4, 2012
[code]The LINQ query going into "result" is incomplete because I'm stumped at what is happening there. I expect FirstOrDefault to refer to refer to a single Child object at that point in the expression, but it refers to a collection of child objects. Why? What is the best way to get a list of parents that have no associated child or have a child fitting a particular condition? (My actual code will have one child max, so this sample code is not representative.)I just don't understand what the collection of FirstOrDefault could be referring to. It should really be just 1 value or nothing at all times.
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May 24, 2010
I'm having trouble getting my head around converting a traditional SQL aggregate query into a LINQ one. The basic data dump works like so:
Dim result =
(From i As Models.InvoiceDetail In Data.InvoiceDetails.GetAll
Join ih As Models.InvoiceHeader In Data.InvoiceHeaders.GetAll On i.InvoiceHeaderID Equals ih.ID
[CODE].....................
What I need to really be getting out is ih.Period (a value from 1 to 12) and a corresponding aggregate value for i.ExtendedValue. When I try to Group ih I get errors about i being out of scope/context.
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Aug 6, 2010
Given a table like
ID | Name | City
1 | X | Y
2 | Z | Y
[code].....
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Aug 3, 2011
also i have a table called Orders with several columns, they contain information about the order and store the ID of the Customer they belong to.Question is: how can i query that table with (preferably) linq (the datacontext is from LinqToSql) to return the following dataI want to search for any entry with the matching CustomerID which took place, group them by Year, Sum the Totals respectively and add them to the listview?I now i could use lamda expressions and aggregate, its just not clear how (option infer on,db is a datacontext object,CustomerID is an int32 variable):
Dim Orders = (From order In db.Orders Where order.CustomerID = CustomerID).GroupBy(Function(p) p.Date.Year).GetEnumerator
I reckon i'd have to create an anonymous type like the following:
[code].....
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May 9, 2010
1.print the cars which are fast moving cars.
i have written this code but it shows message Cannot have aggregate function in expression[code]...
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Jul 1, 2009
I am working on an application in Visual Basic Express using an Access 2000 database.I am trying to get athe following SQL query to work but get an error in Access.
The query is:
SELECT [ID], [Title], [Author], [Series], [YearPublished], [ISBN], [CoverPrice], [Style], [Condition], [Signed], [Comments], Count([Title]) AS CountOfBooks, Sum([CoverPrice]) AS TotalCoverPrice
FROM tblBooks
WHERE ID=[@ID];
The error is:"You have tried to execute a query that does not include the spec ified expression 'ID' as a part of the aggragate function."
The query works fine without the 'Count' and 'CoverPrice' count and sum to the query.
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Apr 30, 2010
I have a Dictionary(Of String, Integer) and I'm trying to use the SUM functionality of LINQ to sum up the values, but am having problems with it.
Basically, the structure is:
dic.Add("Sys A", 10)
dic.Add("Sys B", 2)
dic.Add("Sys C", 3)
dic.Add("Sys D", 5)
I want to run a LINQ query to get the sum in one line rather than looping through the dictionary in order to add them up. Does anyone know how to do this? I have the feeling it should be really simple and basic, but I can't get it to work.
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Feb 15, 2012
I need to generate a little over a 1,000 InfoPath-based access requests. I have that part pretty much all figured out. (Generate the XML file in VB.Net using input from a SQL Server Database) It's all pretty straight forward.The hiccup I run into is that in the InfoPath form there is a repeating table (Multiple XML element with the same tag but different data. Here's an example...
<my:RemoteAccessType>CITRIC</my:RemoteAccessType>
<my:RemoteAccessType>MAILX</my:RemoteAccessType>
<my:RemoteAccessType>RDP</my:RemoteAccessType>
<my:RemoteAccessType>VPN</my:RemoteAccessType>
The problem I'm running into is that not all users have all 4 access types. Some have 1, some 3 - Whatever.
[Code]...
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Jul 25, 2011
I have a code in VB .NET:Aggregate item In items Into Sum(item.Value)
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Aug 27, 2011
The code below is used in a Linq to SQL solution, and is in the Load event of a form. It works fine to display an ordered list of people's names, and set the value member to that person's ID. However, I'm going to be using these 'people' comboboxes a lot, so I'd like to put a sub into my Utility code there is only one line in the form's Load event.
I want to call something like: Call ComboboBoxPeople(cbo, tblTurnbackMain, ReportedByID)
The sub would begin like: Public Sub ComboboxPeople(cbo as Combobox, tbl as 'sometype', fld as 'someothertype')
What can I use as the parameter types for tbl and fld?
[Code]...
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Jun 16, 2011
I have something that I want to do and what looks very simple, but I cannot get it to work. I want to build a function that gets as input a xdocument and some other strings. It should have a return that contains a filtered part of the xdocument in a way that I can use it as input for a new Linq function. This is what I mean:
Private Function fncGetFilteredDecendantsOfNode(ByVal xdocDoc As XDocument, _
[Code]...
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Jun 10, 2012
I'm trying to return a single object from an array of objects with linq.[code]...
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Aug 2, 2011
I write the code below. I want to make short using linq count.
Dim query0 = From obj In dtAginglist _
Where (obj.Field(Of String)("CurrentStatus") = "Open" Or obj.Field(Of String)("CurrentStatus") = "Acknowledge") _
[Code]....
I try to use code below but it dosen't work with if source is datatable.
Dim orderCounts = From c In customers New With { _
c.CustomerID, Key .OrderCount = c.Orders.Count() }
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Jun 30, 2009
Given....
Public MasterList as IEnumerable(Of MasterItem)
Public Class MasterItem(Of T)
Public SubItems as IEnumerable(Of T)
End Class
I would like a single IEnumerable(Of T) which will iterate through all SubItems of all MasterItems in MasterList
I would like to think that there is a Linq facility to do this, or an extension method I am overlooking. I need a mechanism that works in VB9 (2008) and hence does not use Yield.
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Nov 1, 2011
How to Aggregate field's numeric value..? in visual basic 2010.i am created a form with a datagridview and a textbox .datagridview binding with a table. in visual basic 2010 and SQL Server 2008R2
table fields and datagridview columns are like below
[Code]...
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May 28, 2012
i have 1 query with aggregate with condition using access
SELECT
HD.No,
SUM(IIf(DT.Status = 'A', 1, 0)) AS One,[code]...
i can run it in access but not in .Net QueryBuilder
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Mar 9, 2010
I do have a datatable filled from a flatfile (say .txt). After the datatable is populated, I manipulate the data. After datamanipulation I want to do some analysis of the content of the datatable. For this analysis, I need to aggregate the data.
To keep it simple, let's say I have single orders of customers in the datatable and now I want to get the total order amount for each customer (SQL: SELECT Customer, Count(Ordervalue) FROM Ordertable GROUP BY Customer).
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Jun 1, 2012
Have seen some solutions for C# but do not know how to solve the issue in VB.NET.
Query:
Dim Query = (From t In myEntities.Bookings
Where(t.Ref = Someid)
Select t.People).Sum()
t.Ref field is an Int and so is t.People.
The SomeId value is the primary key of the related table. This issue is that there will not always be records in the Bookings table with a Ref value of Someid - so the query throws the following error.
I have seen others have got around this problem with catching the error, but from reading up on this and as per the error information it seems there should be a solution (in VB.NET) to cast the query or some of the fields in the query to nullable types?
Error is as follows:
The cast to value type 'Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.
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Jan 24, 2010
I am trying to pass a lambda function to Linq's orderby and cannot get it to work.
The relevant code is:
Dim myordering = Function(m) m.Count
If isAlphaOrder Then
myOrdering = Function(m) m.Key 'Order by Alphabet
[Code].....
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Feb 20, 2011
how to change this Linq to Entities (VB.Net) query to Group by L2_ID column and aggregate the calculated column diff as Sum for the group.
[Code]...
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Jul 2, 2009
I am trying to aggregate a column in a datagridview. I know how to get it to work if I bind a database to it, I have several of them working perfectly, but I have one datagrid that is not bound to a database and for the life of me can not fiqure out
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Mar 30, 2010
VB.NET .NET 3.5 I have an aggregate class called Package as part of a shipping system. Package contains another class, BoxType . BoxType contains information about the box used to ship the package, such as length, width, etc. of the Box.
Package has a method called GetShippingRates. This method calls a separate helper class, ShipRater, and passes the Package itself as an argument. ShipRater examines the Package as well as the BoxType, and returns a list of possible shipping rates/methods.
What I would like to do is construct an Interface, IRateable, that would be supplied to the helper class ShipRater. So instead of:
[Code]...
However, ShipRater requires information from both the Package and its aggregate, BoxType. If I write an interface IRateable, then how can I use the BoxType properties to implement part of the Interface?
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Aug 9, 2009
I'm using VB .NET and I know that Union normally works ByRef but in VB, Strings are generally processed as if they were primitive datatypes.Consequently, here's the problem:
Sub Main()
Dim firstFile, secondFile As String(), resultingFile As New StringBuilder
firstFile = My.Computer.FileSystem.ReadAllText(My.Computer.FileSystem.SpecialDirectories.Desktop & "1.txt").Split(vbNewLine)
secondFile = My.Computer.FileSystem.ReadAllText(My.Computer.FileSystem.SpecialDirectories.Desktop & "2.txt").Split(vbNewLine)
[Code]...
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Apr 12, 2012
I've got a 2 part question: First question: I know that there is a query limit of 5,000 records when querying records, for performance reasons, but is there a limit when doing an aggregate query? If so, what is it? I need only to query the number of records and for one entity I can get a result of 39,000+ records, but for another entity I see an error message like:
[Code]...
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May 25, 2010
I have a query that can be summarised in SQL as follows;
Select
S.StockCode
From
StockToCheck As S
[Code]....
Where the S var is a list of strings. This gives the error 'S' is not declared and points to the S in the function call / join (GetPOSStock). So it does not seem possible to do this in Linq, can anyone confirm?
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Jun 29, 2010
I'm trying to use a nested multi-line lambda Function in VB.NET and am getting an error. Here's what my code looks like:
cartItems = cartItems.Select(Function(ci) New With {.CartItem = ci, .Discount = discountItems.FirstOrDefault(Function(di) di.SKU = ci.SKU)})
.Select(Function(k)
If k.Discount Is Not Nothing Then
[code]....
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Jun 29, 2011
I have the below Linq query that is returning the data but I need to aggregate the columns to group on the Period and Sum the Count columns. How do I go about doing this?
LINQ
from t In tblTimes
join h In tblEngineeringDashboard_CADMachinesCounts on t.ID Equals h.TimeID
Order By t.Period
[code].....
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