Linq To XML - Query Returns Nothing?
Jul 27, 2010I have a XML file on which when I run a Linq query returns nothing in the for loop.
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.net - LINQ Query Returns List Of Empty Objects?
May 3, 2012I have a query that 'selects' object of a type:
Dim l as IList(Of Foo) = (From dataRow As DataRow In table.Select()
Where CStr(dataRow("Column1")) = "A"
Select New Foo(CStr(dataRow("Column1")), _
CStr(dataRow("Column2")))).ToList()
What's happening is that if i set a break-point to the constructor of Foo and step, the constructor is hit and the parameters are loaded with the arguments. However, l has empty Foo objects (the members in every object are Nothing). What could be happening here?
ASP.NET MVC - Linq Query With Count Returns Anonymous Type - How To Display In View
Sep 29, 2011So I'm writing a query as follows:
Dim assSummary = From a In db.Assignments
Join ur In db.UserRegions
On a.Origin.ID Equals ur.Region.ID
[code]....
In the controller I can return the data easily as follows:
For Each c In assSummary
MsgBox(c.Description & " " & c.AssCount)
Next
If I pass the object through to the view using Viewdata("assSummary") = assSummary, how do I display the data? Every method I've tried results in messages about 'VB$AnonymousType_7(Of Integer,String) and I don't know how to retrieve the data from the anonymous type.
Sql - When Run The Query In Query Analyzer, It Returns One Row But When Use The Same Query, No Rows Are Returned?
Aug 19, 2010Here is the code:
Function getData(ByVal id As String)
Dim reader As SqlClient.SqlDataReader
Dim statement As String
[code].....
LINQ Query Is Enumerated - Turn On Some Kind Of Flag That Alerts Me Each Time A LINQ Query Is Enumerated?
Sep 22, 2009I 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.
Asp.net - Web Server Linq To Sql Returns?
Jul 31, 2011Im trying to make a web service in VB.net is their a way that i can return the results that i get from LINQ. ie "return objreturnLINQResults" I have tryed to set my Public Function GetAlarmsByGUIS(ByVal DeptGUID As String, ByVal IdNumber As String) As Linq.DataContext . i just keep getting errors.
Public Function GetAlarmsByGUIS(ByVal DeptGUID As String, ByVal IdNumber As String) As Linq.DataContext
Dim lqAlarms As New linqAlarmDumpDataContext
[Code].....
.net - ActiveRecord Linq/NHibernate Linq Not Building Query Completely?
Jul 14, 2011given 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, 2009if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?
View 1 RepliesAsp.net - Complex Linq Query - Add A .Where() Or .Any() Predicate To Reduce Query Complexity (in VB)?
Sep 14, 2010I 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]....
Xpath Query On An XML Returns 0 Results
Nov 13, 2011I've converted an html to XML and now i want to get all the child nodes nested
within a DIV element with a specific attribute (class="itemInfo").
Because the html that the XML is based on changes from time to time i want to use a more "safe" relative root,[code...]
Problem is that i always get 0 nodes ...I'm sure that something is wrong with my Xpath syntax, just don't know what it is. Here is my code'[code...]
LINQ Query Using The Dynamic LINQ Library?
Mar 31, 2011Forgive 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."
Check If WQL __InstanceCreation Query Returns Results?
Apr 20, 2012how can write code that can check if __InstanceCreation query has returned rows or not. I'm using this code to check for the creation of a file
Private Function CheckForFileCreation() As Boolean
Try
Dim query1 As New WqlEventQuery( _
[Code]....
so I need to know if the query returned > 0 rows, if it did then the function will return true, if the query returned 0 rows then the function should return false. Sorry I am a complete noob with WMI and WQL
Oracle Query Works In SQL+ But Returns No Rows
Oct 24, 2011I am using the OLEDB adapter (Oracle OLEDB) with Oracle 10.2.0.3.0. My code generates the SQL for the query, then when I execute it into an OLEDBDataReader, the HasRows is False. However, if I output the contents of the query string, copy, and paste into SQL+ (logged in as the same user from the same client machine), it returns 993 rows. What gives?? Here's a segment of my code:
[Code]...
VS 2010 : Xpath Query On A XML Returns 0 Results?
Nov 13, 2011I've converted an html to XML and now i want to get all the child nodes nested within a DIV element with a specific attribute (class="itemInfo").Because the html that the XML is based on changes from time to time i want to use a more "safe" relative root,
(something like : "//div[@class='itemInfo']").Problem is that i always get 0 nodes ...
Dim doc As New System.Xml.XmlDocument()
doc.Load("products.xml")
Dim root As System.Xml.XmlElement = doc.DocumentElement
[code]....
Entity Framework Query Returns Same Row Multiple Times
Aug 31, 2011This is my first time using the Entity Framework and I'm getting some confusing results. I know a particular table contains 3 distinct rows when I run this SQL query:
SELECT * FROM mytable WHERE service_month = 201012
When I run this query against the framework however, I get 3 rows, but they are all copies of the first row (VB syntax).
Dim temp = _context.mytable.Where(Function(x) x.service_month = 201012)
Did I set up something incorrectly? This is how I'd do it with LINQ to SQL.
Query Performed Returns Results In Reverse For Some Options?
Apr 6, 2010I am trying to perform a query on an Access 2007 Database Using Visual Basic 2008. My database has a table tblStudents contains a field named Gender with Male/Female options. In VB 2008 I set up a form with a Combo box where the user can select either Male or Female to perform a query and navigate through the returned results. When i choose the 1st option in the Combo box the results are returned in the order. However when i choose the 2nd option in the combo box, i get the results in reverse order which i still could not find the reason why it does that. Here is my Code for the query and the Execute Query Button:
Private Sub DisplayGenderData(ByVal gender As String)
connUsers.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:StudentRecords.accdb;Jet OLEDB:Database Password=testing;"
' Open the connection.
[Code].....
SQL Update Query Returns Error Message Saying Not All The Parameters Have Been Set?
Jul 8, 2010I'm trying to update an Access database by using an OLE connection, retrieving the information from textboxes where the user enters the new information.All the fields in my Access table are required fields, so I have validated that some info is entered in each one of the textboxes and that is the correct data type.But when I run the update query I get an error message saying something like values haven't been entered for some required parameters (my Visual Studio is the Spanish version, so I can't give the exact error message in English).The bit of code where the error occurs is inside the procedure called by my "Ok" button:
Dim campo1, campo2, campo3, campo4, campo5 As String
Dim campo6, campo7, campo8 As Double
Dim campo9, campo10 As Integer
[code]....
(I didn't post the whole code inside the procedure, but of course I'm creating the connection and everything)
The table has 10 fields, and the data is read from the textboxes and stored in variables (campo1, campo2, campo3, etc.), which I'm then using in the "set" query command.
"id" is the first field from the selected row in the datagrid, which I'm sending as a parameter to the procedure called by the "OK" button.The error message shows at runtime, so I'm guessing it's something in the query. Am I writing it correctly?
"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, 2011We 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, 2011How 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.
Query - Access Db Returns Null After Changing Operating System Date?
May 8, 2012I have a select statement which was returning the required values but when I changed the OS date from English(US) to English(UK), it now returns null. I believe the problem is concerned with date since in the query am selecting values where the date from the database is the same as the date in a combobox but I don't know what else I can do. It almost looks like the dates in the combox and in the database are not the same and yet the date in the combobox is actually retrieved from the database and has been returning values fine until I changed the system date format.Here's my select command:
cmd4.CommandText = _
"SELECT sum(brought_qtty), recieved_qtty from brought_coffee, centre_weigh where brought_date=#" & _
dtComb.Text.Trim & "#" & _[code].......
VS 2008 Linq Possible To Use Query In Another Query?
Apr 16, 2011I 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"
Linq To Sqlite - This Returns The Error "Coalesce Used With Type That Cannot Be Null"?
Sep 17, 2010I am using vb.net sqlite.net and dblinq0.20.1 to search a sqlite table on a primary key field.My code looks like this
Dim blb = (From d In db.Data Where d.UID = myuid Select d).Single
This returns the error "Coalesce used with type that cannot be null" .If I search on a nullable field it works fine.
.net - Should Use LINQ For This Query
Sep 4, 2009I'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, 2012Is 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]
View 4 RepliesLinq Query In .net?
May 5, 2009I 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, 2012I 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, 2010I 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].....
Why The Sql Query Is Different On That Linq Query When Run On C# And On .net
Aug 26, 2009if 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, 2009I'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, 2011I 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)?