How do I get Linq to ignore any parameters that are empty? So Lastname, Firstname, etc? If I have data in all parameters it works fine...
refinedresult = From x In theresult _
Where x.<thelastname>.Value.TestPhoneElement(LastName) And _
x.<thefirstname>.Value.TestPhoneElement(FirstName) And _
x.<id>.Value.TestPhoneElement(Id) And _
[code]....
why is this xml
<?xml version="1.0" encoding="utf-8"?>
<items>
<item id="77" cityID="EE12345" cityDatum="15.2.2010. 11:28:35" />
</items>
[Code]....
If you, as some can't replicate these results, here's a screenshot:
The only way I know of is awkward:
'check for empty return
Dim count As Integer = (From s In myEntity.employee Where employeeID = myEmployeeIDVariable).Count
'If there is a record, then process
[code]....
I 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?
What I'm trying to do is to write a generic rss reader that I plug in any URL into without worry if the feed has all the common properties. For instance in my example below I'm looking for pubDate, however if no pubDate exists in the xml I'd like to return the current Date. I cannot seem to get the syntax right though.
Dim xmldoc As New XDocument
xmldoc = XDocument.Load(url)
Dim feeds = From feed In xmldoc.Descendants("item") Select New With { _
[code].....
GOAL: Bind nested ListViews to LINQ generated iQueryable of anonymous type. I want to use LINQ because you can use GroupBy and bind the nested ListView to the 'it' keyword.
SETUP: I have groups of sets of conditions. Each set of conditions is stored in the BillingCodes table. Each group of BillingCodes is stored in the BillingGroups table.
I have a custom object that stores the ID, Name, and NumCodes for each BillingGroup that the user has chosen.I have a collection of these objects called GroupsList that has a list of the groups that the user has chosen.
Problem 1: I can iterate through GroupsList and grab all the IDs. How do I translate the SQL 'WHERE ID IN(a string of comma delineated IDs)' for LINQ to SQL? Is that the best way to do that?
Problem 2: Once I have the list of BillingGroups I need to iterate through each group. For each group, I need to iterate through the BillingCodes. For each BillingCode I need to generate a WHERE clause that has all of the conditions in the BillingCode. I propose something like so:
for each BillingGroup in BillingGroups
for each BillingCode in BillingGroup.BillingCodes
where1 = "..."
next
next
Problem 3: Here's the part where I don't have a clue. I need to dynamically create a query in LINQ to SQL. Keep in mind that I don't know how many groups there'll be or how many codes are in each group.
There are 2 tables:
**transactions**
transaction_id
patient_id
[code]....
I am using ODBC to read data from a pervasive PSQL database and in some scenarios, the date column can contain 00/00/0000 date. I don't really care about invalid dates so is there some way I can convert all of these un-representable dates into Null or some specific date instead of the query failing.
EDIT: The following shows the code I am using and where it is failing:
Private _connODBC As OdbcConnection
Dim dt As New DataTable
_connODBC = New OdbcConnection(txtConnectionString.Text)
_connODBC.Open()
[Code]...
I have a program that auto fills a section on a webpage, how can i tell this command to ignore the textbox if its empty? If i dont the software crashes because the following command needs the box filled in order to proceed.
[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.
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 RepliesI 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."
I've got a new instance of an object in a Linq DBML, but don't know of the test if the a date field is empty.I have tried:
If d Is Nothing OrElse IsDBNull(d) OrElse d <= Date.MinValue Then
TextValue = "nada"
Else
TextValue = FormatDateTime(d)
End If
But the result is "12:00:00 am"
edit: Changed variable name the d
edit: note that the SQL field is nullable
Please excuse my stupidity, I tend to find the traversing XML overly complicated.
[Code]...
Once it gets to staffBio I get an error saying "Object reference not set to an instance of an object." obviously because that node does not exist. My question is how can I assign the value to a variable even when it is empty without having to do a conditional check before each assignment?
I am trying to pass several search parameters to an LINQ expression to retrieve all entries that contain one of the search items.
Example:
Dim query = From p In db.BEW_PROFIL
For Each searchItem As String In searchItems
[code].....
I am finding this weird issue. When I do this > activities.Where(Function(a) (Not a.IsDeleted And a.ParentId = 100) It returns an in-memory query & when I try opening it up, it throws a object not set exception. This only happens when there were no items which satisfied the condition. Shouldn't it be returning an empty set? When there are items satisfying the condition, then it returns a list & works all good.
View 1 RepliesWe 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.
First time poster and new to ASP programming.I have a functional database to where i am trying to add new functionality.I'm trying to add the idea to check if a returned string is empty, if so get value from a backup table which holds historical information. Here is what i have got for the specific part:
[Code]...
In VBE I have a combobox, a button and a listview.
SELECT * FROM table
WHERE description = @cmbDescription.text
My combobox has three items:
1 All
2 Item1
3 Item2
4 Item3
When user will select any Item the query will return the data related to that Item. My question is how to implement if user selects the option ALL in the combobox.
Can anyone see what I'm doing wrong in this
Dim connStr As String = "connection string goes here"
Dim conn As New Odbc.OdbcConnection(connStr)
Dim comm As New Odbc.OdbcCommand("insert into mytable values (0, @P1, @P2, null, @P3, 'n')", conn)
[Code]....
I get "A syntax error has occured." It appears as though my parameters aren't getting replaced with the values I'm telling it to use.
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 the following form and I'm trying to add a error to the page that if the recordset = 0 then there is a message on the web page stating that there were no results. What's the best way to do that?
Imports System.Data.SqlClient
Imports System.Data
Partial Class _Default
[code].....
How do I pass parameters of LINQ DataTables through Functions and Subs
View 1 RepliesMicrosoft Access queries with somecolumnname = [?] do not show up in the list of Views in the New DataSource Wizard in Visual Studio.
The query works perfectly from within Microsoft Access by just prompting for the values of the parameters.
The columns of the query should populate labels on my form based on the values in a couple textboxes.
What is the "best-practices" way to use parameter queries in my .NET application?
I am currently working on downloading the data automatically on this page[url]...
I would like to somehow be able to control the URL so that, say, when I use the [URL]..
the option selected for Location parameter would be PJM and when I do[code]...
I have a LINQ query:
VB
Dim Db = New MyDataContext
Dim Qry = From cust in Db.Customers
Select cust.ID, cust.Name
And I want to pass it to a function to filter it, like this:
VB
FilterAnyQuery(Qry, cust.ID) ' WHERE "cust.ID" CAN BE ANY FIELD
The Sub should be of this kind:
VB
Sub FilterAnyQuery(ByVal AnyQry As iQueryable, AnyField as ???)
AnyQry = AnyQry.Where(AnyField = "somevalue")
End Sub
How can I pass "AnyField" to the Sub and make the LINQ "Where" clause work?
When I run this code :
Dim username As String = TextBox1.Text
Dim pass As String = TextBox2.Text
Dim con As New OleDb.OleDbConnection con.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;
Data Source=""C:Documents and SettingsSaeedMy DocumentsVisual Studio 2008Projects
[Code] .....
I get these error message:
"No value given for one or more required parameters." at the line:
dr = cmd.ExecuteReader(CommandBehavior.Default)
what is the error.
I want to query items from countries that are selected from a treeview (with checkboxes). However the number of countries that is selected by the user is not known beforehand. So how can I make a proper query when the number of OR operators is unknown? For example: SELECT DISTINCT Item FROM Countries WHERE Country LIKE @c1 OR @c2 OR @c3 etc� and then add the parameter values based on the selected countries in the treeview. I looked into parameter arrays but can�t make sense out of it really
View 13 Replies