Sql Server - Set A DB Value To Nothing With Linq?
Nov 22, 2011
I have an interesting problem. I'm using visual basic and before saving a row with Linq, I want to set it to nothing, for instance:
element.def = Nothing
But, when I save the element I have a 0 in the database instead of Null. Does anybody know how should I save my item so that element.def = Null?
This is an update, element.def previously had a value and element.def is of Integer? type, so it should be possible to save it as null.
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Jul 31, 2011
Im 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].....
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Sep 14, 2011
I am using LINQ with Entity Framework, and I need to get the SQL server timeCan anyone tell me how can I create a method so it retrieves the current server time?
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Mar 17, 2010
I'm encountering a hang when the program tries to access the fruit database. I've already enabled network access MSDTC on both my development computer and the SQL Server server.
[Code]...
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Jan 4, 2011
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]...
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Apr 19, 2010
I'm having trouble with a LINQ to SQL query getting the min value using Visual Basic. Here's the SQL:
SELECT RC.AssetID, MIN(RC.RecCode) AS RecCode, JA.EngineerNote from JobAssetRecCode RC
JOIN JobAssets JA ON JA.AssetID = RC.AssetID AND JA.JobID = RC.JobID
WHERE RC.InspState = 2 AND RC.RecCode > 0
[code]....
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Aug 6, 2010
Given a table like
ID | Name | City
1 | X | Y
2 | Z | Y
[code].....
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Jan 29, 2012
I'm working on an ASP.NET 4.0 site, which I inherited ownership of. It has a number of existing LINQ datasources pointing to individual tables. For example, to the Patient Encounter Summary table in SQL Server. The problem is in displaying the data there. It's a normalized database, so that table contains (for example) the provider ID, rather than the provider name.
It's simple enough to join the Patient Counter Summary to the Providers table (in SQL)... but how does one do that in ASP.NET? I'm not sure of the correct nomenclature, but the 'mid layer' is VB.
[Code]...
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Jan 24, 2011
I'm using Linq to Sql and have a stored proc that won't generate a class. The stored proc draws data from multiple tables into a flat file resultset. The amount of data returned must be as small as possible, the number of round trips to the Sql Server need to be limited, and the amount of server-side processing must be limited as this is for an ASP.NET MVC project. So, I'm trying to write a Linq to Sql Query however am struggling to both replicate and limit the data returned. Here's the stored proc that I'm trying to convert:
[Code]....
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Dec 2, 2011
I know how to select items from an array with LINQ, but what I can't figure out how to do is access a database using an IQueryable. I connected the database to my project, added two classes from the database to the "LINQ to SQL" .dbml file and saved it. In my programming assignment, I am not supposed to create a data source (table thing) to display the data, but update my own interface manually. In order to do it, I was told to instantiate this:
Private dogs As System.Linq.IQueryable(Of Dog)
(Dog is a class that I added to my .dbml file from the database file)Also, I am told it involves using a method
.AsEnumerable.ElementAt(index As Integer)
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Jul 7, 2009
I have a programmer who is using VB and LINQ; and I have a MySQL database that is running on a linux server. My programmer tells me that:he cannot connect to the MySQL database via LINQ if he was able to connect then it would require all sorts of rewriting I don't know anything about LINQ but I thought it was an ORM. As such, any DB server that is supported should work just fine? Right? OK, so maybe it's not an ORM... maybe it should generically connect to ODBC and render similar results?
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May 3, 2012
I have a stored procedure (I cannot edit) that I am calling via linq.
The stored procedure returns values (more complex but important data below):
Customer Stock Item Date Price Priority Qty
--------------------------------------------------------
CUST1 TAP 01-04-2012 £30 30 1 - 30
CUST1 TAP 05-04-2012 £33 30 1 - 30
CUST1 TAP 01-04-2012 £29 20 31 - 99
CUST1 TAP 01-04-2012 £28 10 1 - 30
I am trying to limit this list to rows which have unique Dates and unique quantities in LINQ. I want to remove items with the HIGHER priority leaving rows with unique dates and qty's.
I have tried several group by's using Max and order by's but have not been able to get a result.
Is there any way to do this via linq?
EDIT:
Managed to convert brad-rem's answer into VB.net.
Syntax below if anyone needs it:
returnlist = (From p In returnlist
Order By p.Qty Ascending, p.Priority
Group By AllGrp = p.Date, p.Qty Into g = Group
Select g.First).ToList
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May 24, 2010
I need to represent the following query using LINQ:
DECLARE @PurchasedInventoryItemID Int = 2
DECLARE @PurchasedInventorySectionID Int = 0
DECLARE @PurchasedInventoryItem_PurchasingCategoryID Int = 3
DECLARE @PurchasedInventorySection_PurchasingCategoryID Int = 0
[code]....
Now, I know that a query in .NET doesnt look like this, this is my test in the SQL Design Studio. Naturally VB.NET variables will be used in place of the SQL local variables.My problem is this: All of the conditions after "WHERE" are optional. In that a query might be made that uses one, some, all, or none of the conditions. V.PropertyID and V.Value can also appear any number of times.In VB.NET I can make this query easy enough by simply concatenating strings, and using a loop to append the "V.PropertyID/V.Value" conditions.I can also make a Stored Procedure in MS SQL, which is easy enough.However, I want to accomplish this using LINQ.
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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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Apr 20, 2011
I have a listbox on my xaml form that I bound to a List(Of MyType) property. I populated this list like so:
Dim fields As List(Of CheckableFields) = New List(Of CheckableFields)
Using context As ITIPEntities = New ITIPEntities()
Try[code]....
Now I'm at the point where the user selects the fields they want included in a report and I need to iterate over the required fields. This is my linq query:
For Each checkedField In _requiredFields
If checkedField.IsChecked Then
If checkedField.FieldData IsNot Nothing AndAlso checkedField.FieldData.Trim IsNot String.Empty Then[code].....
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Sep 10, 2009
Example-I have a person class
Public Class Person
Private _fname As String
Public Property Fname() As String
[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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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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Feb 28, 2012
The pattern I'm trying to avoid is checking if a string (normally a control's text value) is null/empty, and if it is, comparing it using Contains to a field in my data. Obviously the field isn't hard-coded into my extension, neither is the object type.What I've got works perfectly in Linq to Objects, but I get the generic run-time error "LINQ to Entities does not recognize the method 'System.String Invoke(GenericQueryHelper.Customer)' method, and this method cannot be translated into a store expression." when using an entity framework model.
Here's what I have:
<System.Runtime.CompilerServices.Extension()>
Public Function CompareAndFilter(Of T)(source As System.Linq.IQueryable(Of T), expressionField As System.Linq.Expressions.Expression(Of System.Func(Of T, String)), compareTo As String)
[code]....
I want my usage to look something like this:
Dim results = repository.Customers.CompareAndFilter(Function(c) c.FirstName, searchText)
I do need to get this running against a SQL database really, as it is filtering results, so I don't want to be doing that in memory.
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Jun 27, 2012
How can I convert this code LINQ to SQL in C # LINQ to SQL in Vb.net
[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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Oct 21, 2009
How can I convert an object of type System.Data.Linq.DataQuery to System.Linq.IQueryable?I'm working with Visual Basic/Silverlight, and the source code of my query is as follows:
Public Function Get_Cli_Pag() As IQueryable(Of V_Cliente_Pagare)
Dim Qry = From P In Me.Context.Pagares Join C In Me.Context.Codigos On C.Codigo
[code]....
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Apr 20, 2010
I just upgraded a project from VB 2008 to VB 2010. Before, the project did not use LINQ. I have started implementing it. So, I have updated the target framework from 2.0 to 3.5, and added a reference to System.Core, and imported the namespace System.LINQ to the entire project and also imported System.Data.LINQ into the form I'm working with (because it was not available in the list for Imported Namespaces in the references tab).
It's not throwing any errors now, but my IntelliSense is not working for LINQ stuff.
For example... I write this:
[CODE]....................
Then, if I type S. on the next line, the IntelliSense doesn't grab what it should for S (Only get Equals, GetHashCode, GetType, ReferenceEquals, and ToString, instead of the options I should get like Count, First, FirstOrDefault, etc...). If I Type S.First. then its the same thing, no IntelliSense that lists the available fields for S, just the standard options (Equals, GetHashCode, GetType, ReferenceEquals, and ToString). I should be seeing my column names in my table when I type S.FirstOrDefault.
So any ideas what is going on? When I type the code, for example, MessageBox.Show(S.FirstOrDefault.FirstName), it works perfectly. But it doesn't change the casing of the text (so it would read s.firstordefault.firstname) and no intellisense while doing it. But no errors. BTW - Everything works perfectly when creating a NEW VS 2010 application, it's just my projects upgraded from Visual Basic 2008 that have this issue.
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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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Feb 22, 2012
I recently switched from VB to C# and have, for the most part, been able to make the transition without too much trouble. Currently I am working on converting a VB.Net program into C# and am having trouble with a couple of code blocks that include Linq.
This is one of the VB.Net lines of code that I am having trouble with:
I have tried to do the same thing in C# like this:
I am getting a compile error on the dt, which says Could not find an implementation of the query pattern for source type 'System.Data.DataTable'.'GroupBy' not found. VS also has issues with the whole into Emailers = group;
I have tried to get this right using examples from my search but have not been able to get it right.
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Sep 7, 2010
I am using stored procedures in my application using vb.net, while executing stored procedures on mysql database server thru application, the response time from the server is more. Is there any settings that i need to set on mysql db server or any changes in connection string or in code.
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May 29, 2012
I have an application I have developed which works great on individual PC's. However I've had some interest from a few customers that asked if I have a network version for site licencing.If my app did not save any data or write any reg entries, this might have been ok. But it does to the local computer. I also built in my own copy protection and trial function that stores data in the registry on the local computer.What would I need to do to enable my application to run on a server/network share, so that the only a serial number needed is for the server?
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Sep 30, 2011
I am writing a custom application for IMAIl express 11.5 using IMAIl Server API for .Net
I am using the following code:
Dim DomData As New DomainData()
DomData.Aliases = "TestALias"
[code].....
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Jul 25, 2010
I have a server which has around 300+ users on it. Though the problem is that its coded in VB6, and if somebody has a bad ping, everybody has a bad ping. I need a tunneling server which will tunnel the incoming and outgoing connections and make there ping appear to be 0 in the server. Client to Server, Server to Client.
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