'Initialize The Database Connection'
Dim dbTRCoreDatabase As New TRCoreDatabase
'Query For Get The Employee ID'
Dim listEmployeeID As IQueryable(Of Long) = (From EmpMaster In dbTRCoreDatabase.EmployeeMasters Where EmpMaster.Email = [code]....
I have two module-level variables and Linq query. I want the results of the Let clause to change the global variables - is this possible?
For example:
Dim X As Integer = 0
Dim Y As Integer = 0
[code].....
I'm making an app using wpf and vb.net in vb2010 express and having a problem. I have a timer that execute a backgroundworker every minute:
Private Sub timer_Tick() Handles timer.Tick
If Not bworker.IsBusy Then
bworker.RunWorkerAsync()
End If
End Sub
The backgroundworker is working with xmlelement and xmldataprovider:
Private Sub bworker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bworker.DoWork
Dim source As XmlDataProvider = Application.Current.Resources("r1")
Dim sometext As String = "something"
Dim elemento As XmlElement = source.Document.CreateElement("elemento")
elemento.InnerText = sometext
e.Result = elemento
End Sub
Then I'm using e.Result on RunWorkerComplete to add the XmlElement to source. It works perfect the first time I execute the backgroundworker, but when the timer calls it the second time it throws a InvalidOperationException in the line "elemento.InnerText = sometext" why is that and how can I solve it?
I've recently been trying to figure out a way to get parameterized queries to work and i think i'm almost there but seem to be getting an error when executing my query
Here's the code
[code]...
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.
I was looking at using linq to sql (or EF) rather than in linedynamic sql within my application but have hit a possible issue. My application modifies data against any number of random databases accross several sql instances, linq appears to structured towards a single database scenario. Would it be best to just continue using in line sql or is there a method of using linq without tying it down to a single database? An example of what I'm doing at the moment:
[Code]...
I`m now at the point calling server from vb.net, and run query inside vb.net code.I have write two codes on button click. One button is checked server connection, other should execute query for server table.Connection code is working, as I have set two messages, and getting successfull message. Second code is not working, as nothing happened when press button. Sql statement is very simple, and it works if I run it manually.[code]
View 19 RepliesI have a string qText with the text of a query in it, say qText = "select * from Data". how can I execute it to fill a TableAdapter I have in my form with the resulting data?
View 2 RepliesImports System.Data
Imports System.Data.SqlClient
Imports System.Configuration
[code].....
What's wrong with my code, the query seems to be fine, I tried executing it on phpmyadmin.
CODE:
I got this error: ERROR [42000] [MySQL][ODBC 5.1 Driver][mysqld-5.1.36-community-log]You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1
I am writing a program that has a listbox which is bound to a dataset. When I click a button (e.g. delete) the item is deleted from the database ok using an SQL query but is still shown in the listbox. How do I get the listbox to refresh/update its display?
View 8 Repliesi am using vb.net 2008 and msaccess i have given the following query to fill a dataset but it is giving me an error. mCmd = " SELECT OfficialInfo.*, "
[Code]...
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
if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?
View 1 RepliesOk I'm creating a sql query with a string variable and executing it in vb. The string would look something like: Insert Into Table (vara,varb,varc) Values ('vara','varb','varc') This works fine.
[Code]...
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]....
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."
What in this block of code would throw this exception?
'Get Highest Revision Number
If MyExtract_BTR.RevisionBlocks.Count > 1 Then
Try
[code].....
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]....
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.
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"
I have a problem with a sql query. Through the query I am trying to search database for any occurrences of string (can be anything) in a column using the SQL LIKE command. The problem is that it works fine for most of the strings say john, jim, ji"m , but does not work when i include the following characters which are ( ' , { , } , and a single quotation mark). MYSQL query takes care of these special cases by putting them in [] block whenever user enters them .But i am getting the following error when i go to query the database using the GetSelectCommand() in VB.NET
Exception Details: System.ApplicationException: Number of values provided must be equal to the number of placeholders in query.I have checked the query over and over again .. but its fine .My database server is Sql Server 2008.So my application throws the exception in this command:
Using reader As MustDisposeDataReader = _
pmSystem.DatabaseManager.GetSelectCommand(selectStatementBuilder.ToString(), New Object() {})
Where MustDisposeDataReader is an instance of a class in an internally developed library, which inherits from System.Object. pmSystem is an instance of the class PlanManagerSystem which implements the commandlayer. GetSelectCommand() takes the select command
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?
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]
View 4 RepliesI have below XML file
<?
xml version="1.0" encoding="utf-8" ?><
PageFlow>
<
attributegroup name="Search"><
attributes>
[Code]...
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
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].....
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" ?
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]....
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)?