VB Syntax For LINQ Query That Creates A New Set?
Dec 3, 2009
I am trying to AVERAGE 6 different fields on a DataTable, but without grouping. Just the AVERAGE. I have found a couple of examples in C#, but can't find any examples for how to do this in VB.Here is what I have so far:
Dim query = From dtRow In dtIn.AsEnumerable _
Where dtRow.Field(Of String)("FOLLOWUP") = "Alert" _
Select New With { _
.Brand_Functional_Avg = XXX.Average(Function(f) f("Brand_Functional")), _
.Brand_Personal_Avg = XXX.Average(Function(f) f("Brand_Personal")) _
}
What should I use for XXX? I tried all of the options that I could think of and nothing is compiling.
Trust me, if I could write this in C#, I would, but the project requires VB.
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Feb 25, 2011
I have a query that I cannot seem to replicate in expression method chain syntax. I have two tables "User" and "UserPayment". User and UserPayment have a one to many relation i.e. One User can have many UserPayments.
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Sep 13, 2011
What is the proper syntax for this:
Dim qry As <??> = From f In dirInfo.GetFiles("*.QBW") Select File = f.FullName, Include = True
Dim dt As DataTable = qry.CopyToDataTable()
I tried as "IEnumerable(Of DataRow)" but that didn't work. At runtime it said:
Unable to cast object of type
'WhereSelectArrayIterator2[System.IO.FileInfo,VB$AnonymousType_02[System.String,System.Boolean]]'
to type
'System.Collections.Generic.IEnumerable`1[System.Data.DataRow]'.
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Sep 22, 2009
I know that LINQ queries are deferred and only executed when the query is enumerated, but I'm having trouble figuring out exactly when that happens.Certainly in a For Each loop, the query would be enumerated.What's the rule of thumb to follow? I don't want to accidentally enumerate over my query twice if it's a huge result.
For example, does System.Linq.Enumerable.First enumerate over the whole query? I ask for performance reasons. I want to pass a LINQ result set to an ASP.NET MVC view, and I also want to pass the First element separately. Enumerating over the results twice would be painful.It would be great to turn on some kind of flag that alerts me each time a LINQ query is enumerated. That way I could catch scenarios when I accidentally enumerate twice.
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Oct 31, 2011
I have 7 company Divisions that sit in an access database.I then use this list to populate two comboboxes in my windows form.However I get a syntax error in my SQL Query if the Division name is more than one word.For example in my access database I have two columns one is a status column and the other is a division column. If for example the Division is called 'Corporate' the status column is called 'Status Corporate' and the division column is called 'Corporate'.The SQL query works fine in this scenario.However if I have a Division that is more than one word, lets say 'Operations Division' I get an error in my SQL Query that says -
Quote: Syntax error (missing operator) in query expression 'Operations Division'.Here is my code
sqlNewTenderDetails = "SELECT " & Me.DivisionBox.SelectedValue & " From BidRefCodes Where " & "[Status " & Me.DivisionBox.SelectedValue & "='Active'"
daNewTenderDetails = New OleDb.OleDbDataAdapter(sqlNewTenderDetails, NewTenderDetailsTableCon)[code]....
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Jul 14, 2011
given this function:
Public Function Search(ByVal StartIndex As Integer, _
ByVal MaxResults As Integer, _
ByVal AccountNumber As String, _
ByVal LastName As String, _
[Code]....
instead of what I expected:
Select count(*) from remitline where lastname = "smith"
What am I doing wrong building up the where clause? I'm using Castle ActiveRecord 2.1
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Aug 6, 2009
if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?
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Sep 14, 2010
I have to join two main tables, and I need to filter the results by elements in an ASP.NET web form. These filters are created on the fly so I have to use a lot of where extensions to filter the query. I want to execute the query with as optimized SQL as possible.
I am first doing a simple join between TW_Sites and TW_Investigators. Then there are two sub-tables that are involved. TW_InvestigatorToArea and TW_InvestigatorToDisease. While most of the where clauses are working fine, I have found a performance issue that won't be an issue right now, but will be an issue as the table gets bigger.
The arrays DiseaseCategories and DiseaseAreas would be the results of a CheckBoxList result.
Protected Sub LoadResults()
'Get Dictionary of Filters
Dim FilterDictionary As OrderedDictionary = Session.Item("InvestigatorFilterDictionary")
' Initialize LinqToSql
[code]....
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Mar 31, 2011
Forgive my ignorance on this.I have this LINQ Query:Dim ngBikersDataContext As New CarBikeWalkDataContext
bikersList = (From c In ngBikersDataContext.Reg_Bikers _
Order By c.L_Name _
Select New Bikers() With { _
.BikerID = c.BikerID, _
.F_Name = c.F_Name, _
[Code]...
with the error "Overload resolution failed because no accesible 'Select' accepts this number of arguments."
Over the "NEW" I get an error " ')'expected."
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Jul 14, 2009
tell me the equivalent syntax for the following code in VB.net?
Static Class TestList
{
static void Main()
{
[code].....
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May 4, 2011
I ran into this answer which had a triple dot syntax in VB.NET that I have never seen before. The query looks like this
[Code]...
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Jun 29, 2011
After I have programmed several projects in VB.Net I to my surprise discovered that there are some more than subtle differences between C# and VB.NET LINQ usage.For example, if we want to group elements by multiple properties (columns) we need to create a new anonymous type explicitly:
var procs = from c in Process.GetProcesses()
group c by new {c.BasePriority, c.Id} into d
select d;
whereas in VB.NET more straightforward syntax will already do:
Dim b = From c In Process.GetProcesses()
Group c By c.BasePriority, c.Id Into Group
Select Group
So, one does not need to create a type with "new" here. What are the other differences? good comparison between the LINQ syntax in C# and VB.NET?
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May 5, 2009
I'd like to do a subtraction of sets based on criteria. A pseudo-query would look like:
select table1.columnn1
,table1.column2
from table1, table2
[Code]....
I can make it to about here:
dim list = From tbl1 In table1 Where tt.column1 ...
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May 28, 2009
What I really want is to select these two tables in to an anon type like in Scott Gu's blog: here However, I would settle for this created type "ActiveLots" I am joining two tables together and want to be able to reference columns from each in my result set. [code]...
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Jan 27, 2011
We are doing a query against an in-memory collection of LINQ data objects. The wrinkle is that we are ordering by a column in a related table whose records have not necessarily been loaded yet (deferred loading:)
Dim oPkgProducts = _
From b In oBillPkg.BillProducts _
Where b.Successful.GetValueOrDefault(Common.X_INDETERMINATE) = _
[code]....
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May 13, 2009
I'm a bit of a LINQ newbie and I was having some trouble with the following. I'm trying to perform a query using LINQ on an XML file and store the results in a list of DataClass objects that match the XML.I've got an XML file that is defined like this:
<NewDataSet>
<NewDataTable>
<Field>Accepted ASNs</Field>
<Val>59</Val>[code]....
I have created a Data class to support this XML format. What I would like to do is create a LINQ Query to grab these 3 records and store them into a List of my DataClass. In order to support multiple Order elements, I have my class defined with a generic list of "Order" structs... It looks like this:
Public Class ASNData
Private _field As String
Private _value As String[code].....
how to grab the 3 order elements and store them into my list of Order structs.
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Dec 10, 2010
I have the following XML file
<Test>
<Modules>
<Module Name= "Test1">
<QueueName Name="Test1Active1" Active="True"></QueueName>
<QueueName Name="Test1Active2" Active="True"></QueueName>
[Code]...
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Aug 6, 2010
I'm trying to grasp the linq to xml 'inline query syntax' features of VB.Net First I tried with this simple xml file:
<?xml version="1.0" encoding="utf-8" ?>
<Root>
<Child Name="somename">
[code]....
This xml, when loaded in an XDocument, can be loaded and queried as follows:
Dim xdoc = XDocument.Load("sample.xml")
Console.WriteLine(xml.Root.<Child>.@Name)
Then I change the <Root> element in the sample xml file to:
<Root xmlns="http://SomeNamespace">
Now I can't seem to use the convenient 'Axis Properties' syntax anymore... I can only get it to work with the explicit XElement syntax:
Dim ns As XNamespace = "http://SomeNamespace"
' works, but I would like to use the same syntax as above...
Console.WriteLine(xdoc.Descendants(ns + "Child").First().Attribute("Name").Value)
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Jan 24, 2012
I am building an xml file with the help of Linq queries and I'm not sure why the code below doesn't work.[code]
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Aug 31, 2011
How do I add ROW_NUMBER to a LINQ query or Entity? How can I convert this solution to VB.NET?
[Code]...
I'm having trouble porting that last line. I have been unable to locate a VB.NET example. I'm actually not looking for any paging functionality like the example provides, just good old-fashioned Row_Number(Order By X) row index.
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May 25, 2011
I have a LINQ to sql statement that joins 2 tables. I would like to add a order by clause on one of the columns. However the order by clause does not seem to take effect at all. right syntax in VB.net to achieve order by in the following:
Dim query = From dtIt In dbsomecontext.mytable
Join dtIl In dbsomecontext.anothertable On dtIt.ItemID Equals dtIl.ItemID
Where dtIl.IsAvailable = True
Order By dtIt.manufacturer
[Code]...
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Apr 16, 2011
I was wandering is it possible to use a query within another query below is the code I am trying to use.
Public Function GetInventByComp(ByVal CompID As String) Using DC As New DataClassDataContext
'need to get company id's based off names? thats bad should be name from Id need to rethink this
Dim invent = (From C In DC.Inventors_Companies _
Where C.CompID = CompID _
Select C.InventorID).ToString
[Code]...
I was trying to us multiple values in a string like "1, 3, 5" but I can't seem to get that working either so I am trying to use just a single value now. Can anyone help me? "Yes I am new to this"
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Jul 14, 2009
I've been trying to write this snippet of code in VB, can anyone see what is wrong with it? I am recieving an error on line 5.
Dim a1 = From rows In db.tPDMLinkUsages _
Where (rows.ACCESSDATE >= DateTime.Today.AddDays(-90)) _
Select New With _
{ _
[CODE]...
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Jun 29, 2010
I'm trying to translate some C# LINQ code into VB.NET and am stuck on how to declare an anonymous type in VB.NET.[code]How do you translate C#'s new { ... } syntax into VB.NET?
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Mar 25, 2012
I am having problems implementing this query in vb.net.The error message that I am getting is with the "as" in the first line.This is a local sql compact database 3.5
cmd.CommandText = "UPDATE player as a " &
"SET starter = 'TRUE' " &
"WHERE NOT EXISTS (SELECT '1' " &
[code]....
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Aug 1, 2011
i am having an sql query in catch block. the code is:
Dim str_exception
As
String = ex.Message
Dim sql5
As
[Code]...
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Mar 23, 2012
My code is supposed to select the month fand see what product ahas been sold and how much has been sold. It does it but i keep getting a Incorrect syntax near '='. and i cannot fix
CODE:
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Jan 10, 2012
Command = New OleDbCommand("SELECT dbo.tbl_staff.staff_id, dbo.tbl_staff.username, dbo.tbl_staff.password, dbo.tbl_useraccount.position_id " & _
"FROM dbo.tbl_position INNER JOIN " & _
[code]....
It says incorrect syntax.
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Oct 29, 2010
Showing Syntax error in Insert Query.[code]but i have checked the query and tested it but there is no error.[code]
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Apr 15, 2012
Inline Code Example Here
con.Open()
cmd.Connection = con
[code].....
The above is my query for my datagrid view nd it keeps saying
Incorrect syntax near '.'.
but when i do it in the query bulider in sql server it is fine?
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