Loop Through LINQ To SQL Query?

Mar 12, 2012

Here's my query dim areas = From job In db.jobs Join area In db.areas

On area.JobID Equals job.JobID
Where job.JobID = id
Select area.Area, area.UnitID

I have two controls in my form

2 textboxes: tbArea1 and tbArea2
2 comboboxes: cbArea1Units and cbArea2Units

I've traditionally used a ForEach loop to cycle through LINQ to SQL results, but this instance doesn't seem to work. By design in the database, the result will always only return up to two possible areas, but no more then that. How can I populate the textboxes and set the SelectedValue of the comboboxes to something like this?

[Code]...

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For Each Loop - Involving LINQ Query When Reading Form Controls

Dec 8, 2009

I have a form with a tab control, containing a small number of tab pages. I'm writing a sub procedure to clear the controls within a groupbox for the selected tab. A selected tab will only ever contain ONE groupbox and within a groupbox will be command buttons, labels, text boxes and possibly a combobox. The first block of code below firstly finds the groupbox within the selected tab. The next part loops around all control type and if of type texbox clears the text.

Now hears the head scratcher/confusion it error's with :-
Unable to cast object of type 'System.Windows.Forms.Button' to type 'System.Windows.Forms.GroupBox
Which I don't understand as I cant see where Im converting objects simply looping through all controls and then ONLY if type of control is textbox then clear text.

'Loop around all controls in form, simplified that all controls
'are within a SINGLE groupbox and clear contents or reset to default value
Dim groupbox = (From grpbx In tabAdmin.SelectedTab.Controls _
Select grpbx = DirectCast(grpbx, GroupBox) _
Where TypeOf grpbx Is GroupBox)
[Code] .....

LINQ Query With Multiple OrderBy Statements Added In Loop

May 11, 2012

I have a method in a webservice that has parameter with which users can decide how they want to order their results. This is a List(Of String) with the names of the fields in the order they want to sort them. I know I can normally order on multiple columns by doing the following

Dim test = Bars.OrderBy(Function(x) x.Foo) _
.ThenBy(Function(x) x.Bar) _
.ThenBy(Function(x) x.Test)

However in this case this won't work since I can't chain the ThenBy function because I'm adding the sorting orders in a loop. To use ThenBy I need an IOrderedQueryable collection. This is how I would want it to work

Dim sortColumns = {"Foo", "Bar", "Test"}
Dim query = From b in Bars
For each column in sortColumns
Select Case column
Case "Foo"
query = query.Orderby(Function(x) x.Foo)
[Code] .....

LINQ Query Is Enumerated - Turn On Some Kind Of Flag That Alerts Me Each Time A LINQ Query Is Enumerated?

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.

.net - ActiveRecord Linq/NHibernate Linq Not Building Query Completely?

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

Performance Gain In LINQ Query Vs LINQ Stored Procedure?

Aug 6, 2009

if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?

Asp.net - Complex Linq Query - Add A .Where() Or .Any() Predicate To Reduce Query Complexity (in VB)?

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]....

LINQ Query Using The Dynamic LINQ Library?

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."

"System.ArgumentException: An Item With The Same Key Has Already Been Added." When Trying To Order An In-memory LINQ Query By A LINQ Association?

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]....

LINQ To SQL - Add In Row_Number To A LINQ To SQL Query?

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.

VS 2008 Linq Possible To Use Query In Another Query?

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"

How To Loop Through LINQ Results

May 17, 2010

I've got some code to try and loop through LINQ results, but it doesn't seem to be working.

HERE'S THE CODE

Public Sub ProcessRequest(ByVal context As System.Web.HttpContext) Implements System.Web.IHttpHandler.ProcessRequest
''# the page contenttype is plain text'

[Code]....

.net - Should Use LINQ For This Query

Sep 4, 2009

I've been reading a fair bit about the performance of using LINQ rather than using a for each loop and from what I understand using a LINQ query would be a little bit slower but generally worth it for convenience and expressiveness. However I am a bit confused about how much slower it is if you were to use the results of the query in a for loop.

Let's say that I have a set called 'Locations' and a set of objects called 'Items'. Each 'item' can only belong to one 'location'. I want to link items that are under the same location to each other. If I were to do this using a normal 'For Each' loop it would be something like this:

For Each it as Item in Items
If it.Location.equals(Me.Location)
Me.LinkedItems.Add(it)
End If
Next

However if i was to use LINQ it would instead be this:

For Each it as Item in Items.Where(Function(i) i.Location.equals(Me.Location))
Me.LinkedItems.Add(it)
Next

is the second (LINQ) option going to loop once through the entire 'Items' set to complete the query, then loop through the results to add them to the list, resulting in essentially two loops, or will it do the one loop like the first (For Each) option?

Can Do A LINQ Query Of A LINQ Query?

Mar 24, 2012

Is it possible to do the following? [code] Basically I have one Load_Gridview function that is called on all postbacks, and rather than creating a bunch of different cases.I want the filters to stack.My actual code has more filters set up (4 or 5 of the).It all compiles ok but when I run and try to execute with active checked, or a department selected I get the following error. [code]

Linq Query In .net?

May 5, 2009

I have below XML file

<?
xml version="1.0" encoding="utf-8" ?><
PageFlow>
<
attributegroup name="Search"><
attributes>

[Code]...

Put A Sum() In Linq Query?

Apr 18, 2012

I am looking to sum the "Status" field.

Dim _detailRecords As New DataTable
_detailRecords.Columns.Add("y")
_detailRecords.Columns.Add("z")

[Code]....

I'm also wanting to keep this as an IEnumerable of DataRow because I will be creating a datatable from it with

Dim yyyyy As DataTable = query8.CopyToDataTable

Query With Linq To Xm?

Aug 13, 2010

I am Fairly new to Linq and I am trying to write a simple query to return the error messages within my xml file.

<?xml version="1.0" encoding="utf-8"?>
<Error xmlns="urn:xxxxx">
The following errors were detected:

[code].....

Quicker Way To Loop Through LINQ Data

Oct 22, 2010

I am writing code that pulls data from database tables and writes them to an XML file (to be picked up by another process). There are bout 60,000 records, and each record can have multiple entites, i.e. a member can have several contacts, each contact can have several phone numbers, etc. The entire process takes several hours, and I've narrowed down the slowness to the actual pull of the data (not writing the XML, or any data processing after it's pulled, etc.). I've tried the code two different ways, with similar results. First I leveraged LINQ queries and created all the elements in one statement:[code]That produced almost no change in amount of time the process took. I then tried stripping out all the elements and reduced the code down to just the database pulls, and it was similarly slow.Is there a faster/better way to pull all this normalized data from the database so I can get it to the XML file as quickly as possible?

Why The Sql Query Is Different On That Linq Query When Run On C# And On .net

Aug 26, 2009

if I run this under c#

from p in Addresses where p.Address2 == null select p.AddressID

it generate this query

SELECT [t0].[AddressID]
FROM [dbo].[Address] AS [t0]
WHERE [t0].[Address2] IS NULL

if I run this under vb.net

from p in Addresses where p.Address2 = nothing select p.AddressID

it generate this query

SELECT [t0].[AddressID]
FROM [dbo].[Address] AS [t0]
WHERE [t0].[Address2] = ''

p.Address2 is a varchar field that accept null value

why vb.net is "wrong" ?

.net - Converting Linq To XML Query From C# To .Net?

Dec 1, 2009

I'm converting the Linq query below from C# to VB.Net. Can you spot my error? The query joins 3 XML datasets. C# - This one works great.

List<Course> courses =
(from course in CourseXML.Descendants(ns + "row")
join coursecategory in CourseCategoryXML.Descendants("Table") on (string)course.Attribute("code") equals (string)coursecategory.Element("DATA")

[code]....

.net - Dynamic Linq Query?

Mar 14, 2011

I have been trying the following but it returns unexpected results:

Dim xd As XDocument = _
<?xml version="1.0" encoding="utf-8"?>
<root>

[code].....

The above result returns both 'element' nodes however it should only return the first where element/subelement@id=1/subsubelement@id=3 However if results.Ancestors. is used it returns the correct 'subelement' and if that line is not included it returns a single 'subsubelement' whih is also correct I don't understand why when mvoing to the 'element' it returns both (I realise both have a subelement with id=1 but I thought each further query would filter out the presvious results)?

.net - LINQ C# Query In VB - Getting An Error

Feb 22, 2012

I have a List of Price Objects (Price contains Date, High, Low) and am trying to extract monthly averages via LINQ. I have this working in C# but we have a few legacy applications that need it in VB.Net and I can't quite seem to figure out the conversion. I've even tried breaking it into two queries to no avail.

[Code]...

.net - Linq Query If Statement?

Jun 24, 2011

Ok im trying to do a if statement in Linq and was wondering if it was possible to do something like:

Dim loadFriends = From p In db.UserRelationships Where p.aspnet_User.UserName = User.Identity.Name _
Or p.aspnet_User1.UserName = User.Identity.Name And p.Type = 1 _
Select New With {if p.aspnet_user1.user = "a certan username" then .username = _
p.aspnet_user.username else .username = p.aspnet_user1.Username}

[Code]...

.net - Linq Query To List?

Sep 2, 2011

Dim query = From o In myContainer.MyObjects Select o.MyStringProperty Distinct
Dim myProperties As List(Of String) = query.ToList????? 'no way!!!'
"query" type is IEnumerable(Of String)

I tried to use the query directly as a DataSource of a (infragistic) combobox, but it throws me NullReferenceException, so I decided to convert it to a listof strings, to be a more "classical" datasource.

Dim values As List(Of String) = query.AsQueryable().ToList()
does not work either: Value of type 'System.Collections.Generic.List(Of System.Linq.IQueryable(Of String))' cannot be converted to 'System.Collections.Generic.List(Of String)'.

.net - Linq To AD Query Not Working?

Sep 20, 2011

user.fld_usr_name is a string with the value random name user is an object that is given as a parameter

ByVal user As GUser

this is the linq query that doesn't work

Dim result = (From usr In users Where usr.Name.Contains(user.fld_usr_name) Select usr).ToList()

this is the one that works

Dim result = (From usr In users Where usr.Name.Contains("random name") Select usr).ToList()

this is the error

Object reference not set to an instance of an object.

I am using this in Linq to Active Directory library which probably means it's linq to entities I've tried everything?

.net Conditional Linq Query?

Sep 27, 2011

In this query against a datatable i'm trying to do some conditional filtering.The check against Timeband(index N) should only be done when the Index exists. (the base code only had three item fields, i've converted them to a simple list)

Dim res As DataTable =
(
From dr As DataRow In dtTimedRow.AsEnumerable()
Select dr

[code]....

The above code triggers an Exception if the count = 1. It executes the code next to imeBands.Count > 1 which it should not. What would be the correct solution for this code.In the mean time i've added a simple filter function.

Asp.net LINQ Join Query

Sep 28, 2011

I have this query that I tried to join 2 tables together, one which holds the product name, and product numbers, and take a product number, and go to the other where to find a Art_no which is like the product number.[code]

C# - VB And IGrouping For LINQ Query?

May 28, 2009

I am converting a c# LINQ example:[code].....

In the above C# the g is an IGrouping but in the VB below it's instead an IEnumerable and thus the g.Key isn't resolving.[code]....

C# Equivalent Of VB LINQ Query?

Jul 20, 2011

I have the following query in VB, but I do not know how to translate it to C# synatax

Dim q = From c In db.Customers
Group Join o In db.Orders On c.CustomerID Equals o.CustomerID Into orders = Group
Select New With {c.ContactName, .OrderCount = orders.Count()}

Dynamic Query Linq To Xml?

Mar 16, 2011

I want to write a query that the "where" in the query is a string something like"

Dim query as string= "Name =xxxx and Date > 10 "
Dim t = from book in doc.Descendants("books") Select _
[Name] = book..value, [Date] = book..value....
Where (query)

I build the query string on run time

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