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?
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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.
I need to test a logical expression held in a string to see if it evaluate to TRUE or FALSE.(the strig is built dynamically)For example the resulting string may contain "'dog'<'cat' OR (1>4 AND 4<6)". There are no variables in the string, it will logically evaluate. It will only contain simple operators = > < >< >= <= and AND , OR and Open and Close Brackets, string constants and numbers. (converted to correct syntax && || etc.)
I currently acheive this by creating a jscipt function and compiling it into a .dll. I then reference the .dll in my VB.NET project.
class ExpressionEvaluator
{
function Evaluate(Expression : String)
{
return eval(Expression);
}
}
Is there a simpler method using built in .NET functions or Lamdba expressions.
[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.
View 1 RepliesI'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.
Given a table like
ID | Name | City
1 | X | Y
2 | Z | Y
[code].....
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].....
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.
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What is the difference between Equals and = in LINQ?
Dim list As List(Of Foo) = (From a As Foo In FooList _
Join b As Bar In BarList _
On a.Something = b.Something _
Select a).ToList()
versus Dim list As List(Of Foo) = (From a As Foo In FooList _Join b As Bar In BarList _On a.Something Equals b.Something _Select a).ToList()
what is the difference between these 2 ways to refresh a linq class
1) LinqDB.Refresh
2) LinqDB =
New DataClasses1DataContext
I have got the impression that some time the linqdb.refresh does not work at all
I have a code in VB .NET:Aggregate item In items Into Sum(item.Value)
View 3 RepliesGiven....
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.
Did anyone else read this article under Visual Basic News? I thought it was a very bad treatment of the subject. I especially don't like articles like that when the code they post relies on Option Strict Off.
View 12 Repliesi'm trying to find a way to get with vb.net info regarding logical drive such as: Total Size, Free Size and Volume label ame and to write the info to some textbox or somthing similar.
View 8 RepliesSorting arrays are useful when you want to get the first/last/min/max logical item of a list. I.E. A list that contains numbers and you want to find the Min/Max (without LINQ), you can sort the list and pull the first/last element. It's also useful to display lists to the user in alphabetical order.
View 2 RepliesHow 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
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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
According to MSDN The And operator can act as a bitwise operator OR a logical operator.The only way to know if it is used as One operator or another is, If it is on the right side of an assignment operation? for example x = 3 AND 5. I cannot find any other instances where the bitwise operator would be used instead of the logical operator, are there?
View 1 Replies1.print the cars which are fast moving cars.
i have written this code but it shows message Cannot have aggregate function in expression[code]...
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).
I don't know the codes to lock the logical drive What it will be if anybody knows it
View 1 RepliesIs it possible to create a logical serical port in vb that another application can open and read/write to?
View 2 RepliesDisplay Size Of Logical Drives
View 23 Replieshow 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.
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I have the need to express simple conditionals as program input. The input must be human readable. Is XML suited for this? For example, I have the following conditional statement:
If AnimalType = Leopard And (SourceCountry = Kenya Or TargetCountry = Kenya) Then
ZooKeeper=Jack
Else
ZooKeeper=Jill
End If
Expressing the above in XML might look something like this:
<If>
<Conditional>
<And>
<AnimalType>Leopard<AnimalType>
[Code] .....
How best to represent conditional statements in XML? I haven't yet explored using attributes. I don't currently have the need for nested 'If' statements or the 'Else If' clause, but I'm going to try and work them in anyway. Perhaps the VB code is more 'readable' than XML can be in this case and I should create a custom flat-file format instead.
I am listing all logical drives with GetLogicalDrives() function and i am getting that----( A: , C: , D: , K: , M:)[code]If i checks "Get FilesCount (Drive_name)" for A: (Floppy Drive) then I gets error "DRIVE NOT READY".I want CODE WITHOUT THIS ERRORRR Even if floppy drive is empty or a CD/DVD-ROM is empty.
View 1 RepliesI 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
View 4 RepliesVB.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?
Does anyone know the code to address Logical Block 0 of a disk? This is my dump of block 0 of a multipartition disk.
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Can I set up a change in the font color when a certain true value comes up with a logical test - e.g. If the "value_if_true" says STOP, can I have the STOP show up in a red font and if the "value_if_false" says OK, then leave it as a black font?
View 1 Replies