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I am currently learning EF and I am coding a Windows app as part of the learning process.
Given this code fragment:
using (var context = new MovieList_EFEntities())
{
string esql = "select value m from Movies as m Where m.MovieId = " + Convert.ToInt32(movieId) + "";
var Movies = context.CreateQuery< Movie>(esql);
foreach (var movie in Movies)
{
movie.Name = tbTitle.Text;
context.SaveChanges();
}
}
SaveChanges throws an exception - New transaction not allowed.
The Movie entity maps to the equivalent database table composed of 2 fields, the PK (identity) and the Name field. I want to change the Name. Why is the above not permitted?
As a workaround, I created a Movie object with the 2 field values assigned. I did not get the desired effect. My db record was not updated, rather, EF inserted a new record. I will figure this out eventually. Was hoping someone can help me out before I do.
Thank-you.
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You should try to get the movie from the context using LINQ.
using var context = new MovieList_EFEntities())
{
int id = Convert.ToInt32(movieId);
Movie mov = context.Movies.SingleOrDefault(m => m.MovieId == id);
if (mov != null)
{
mov.Name = tbTitle.Text;
}
else
{
}
context.SaveChanges();
}Hope it helps, good luck! 
It's an OO world.
public class Naerling : Lazy<Person>{
public void DoWork(){ throw new NotImplementedException(); }
}
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I figured it out eventually.
I agree with you. Better to use LINQ.
Thank-you for the reply.
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Glad you found it. No problem!
It's an OO world.
public class Naerling : Lazy<Person>{
public void DoWork(){ throw new NotImplementedException(); }
}
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How to Install and use in Windows Xp Created Windows Service via VB.Net??? 
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I have a problem with my project ...
I haven't 'Project Name' in 'Output Project Group' Dialog box...
mean: Nothig exist in this dialog on my project!!!
How can I to Access project information from that dialog box???
modified 4-Jul-12 5:12am.
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Some suggestions:
1. Don't end every statement or question with smileys; use proper punctuation and people are more likely to take you seriously.
2. Think about your problem and try to describe it in clear detail with examples where necessary. Remember that no one but you can see what is on your screen.
In the above:
ICEFLOWER2 wrote: I haven't 'Project Name' in 'Output Project Group' Dialog box
What dialog box are you referring to and which tab: Project Properties or something else?
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Simple Windows Service Sample Simple Windows Service Sample[^]
To add MyNewService.exe to the setup project
In Solution Explorer, right-click MyServiceSetup, point to Add, then choose Project Output. The Add Project Output Group dialog box appears.
MyNewService is selected in the Project box.
From the list box, select Primary Output, and click OK.
of Setup Project ...
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Thank you for your answer ![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif)
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Are you doing ANY research yourself, or do you think that we are here to answer every question that you have instantly? Based on the number of questions you have posted here recently, I would recommend that you read this[^] book as you obviously understand at least some of VB.NET. This book will help to fill the missing bits in your knowledge.
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hi
add setup and deployment project and add project output in your existing windows service.
and add custom action in setup and deploy project
Add Application Directory in that project
Finaly Build Relies mode
vijay
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How Can I Change/Set Registry Keys Access Control to use??? 
Please Leave VB.Net Example...
Thanks...
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The first question is WHY? Why would you want to do this?
The next question is WHERE? Your application really isn't setting any security because the applciation runs as the user. So, you're really not securing anything by letting the user do it.
Any security changes are normally done in the application installer.
But, of course, that depends entirely on what your application does and who's running it.
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The first question is WHY? Why would you want to do this?
For example I have a Bluetooth Device/driver in Device manager like:
<Modem over Bluetooth Link#4>
But that device information in registry has some info more than it like:
<Modem over Bluetooth Link>
<Modem over Bluetooth Link#1>
<Modem over Bluetooth Link#2>
<Modem over Bluetooth Link#3> 
I Want to remove and change to default...
If you know easy way to this please leave source code for it or ... 
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So what do you think changing the security on a registry key is going to do for this??
And which registry key are you thinking of changing??
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And? That picture doesn't answer the questions at hand. What do you think changing the security on a registry key is going to do for this??
It appears that your code isn't checking to see if the modem is enabled or valid in some way.
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Here you go[^].
It's not going to solve your problem though...
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Hello every VB.NEt Experts,
I have one problem with my databindings with datagrid.
I wanna select any cell in datagrid to show and change data according to my selection. when I bound my data already it didn't show anything. CbxPrefix= ComboboxPrefix
My code : <b>CbxPrefix.databindings.Add(New Binding("Text",ds,"Lecturer.PrefixName")) </b>
what's wrong with this code. I forgot I make it in subroutine named Private Sub BindDgvLecturer......End sub and put it in Form1_load.
Please help me with this problem. Thank you very much.
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How Can I have a List of System Devices via VB.Net Coding
and I want to access for install, UnInstall and other information about those
Thank you... (me)
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What about VB.Net...
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No problem. WMI can be used with both VB.Net and C#.
This article[^] might help you start VB.Net and WMI.
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