problems add new record on entity framework - Visual Basic Discussion Boards

Hi all...

I am going to make a multi-user database application in VB.NET (VS 2008).

I have made several db program using different databases and made some client-server based chat programs. But I never worked on multi-user db program.

I wanna know that which database should I use as back-end. Application will be accessible by 3-5 users.

I also wanna know that from where to start to build multi-user program.

Suggest me.

Thanks.

Gagan

Assuming you're not storing ridiculously massive amounts of data, SQL Server Express would be a reasonable choice. Actually, pretty much anything but Access would be reasonable - there are way too many WTF's created by trying to make a multi-user Access system!

Personally, I use MySQL as the database and I connect my client application using WCF services.

Live for today. Plan for tomorrow. Party tonight!

Go with Sql Server Express, and get the Sql Server Management Studio to go with it. They're free, and should work for you. I think the db limit is now up to 10 gigs

Hi, I am looking into using Codility.com for screening newhires, anybody heard about it or better used it for anything serious?
Thanks
Thanks for help.

MadMax2011

Why did you choose the VB section for this post?

Would one of the other section not have been more applicable e.g. 'Running a business' or 'Work Issues'

Dave
Find Me On: Web|Facebook|Twitter|LinkedIn

Folding Stats: Team CodeProject

I opened the demo-test, and closed it as soon as it finished loading. The problem-statement was an academic description, not a practical one - and it seems to measures success, not efficiency.

Must have been a nice and cool exercise to write, but it's not a tool I'll be using.

Bastard Programmer from Hell Suspicious | :suss:

Hello !
i have a sql server 2008r2 database ( stu) with a table (st) with these columns :
stID - identity (int autoincrement value)
name - char(10)
com - char(20)

i have a project in vb.net 2010 , and i have generated entity framework model with the database.
I have a form with a listbox and 2 textbox , and 2 buttons Addrecord and Saverecord.
The listbox is bound with an object from entity (stBindingSource) and displayMember: name , Valuememeber : stID. The form is also binded with stbindingsource. ( textbox1:name , Textbox2: com)
I want to add new record.The code is :
……-----------------------------------
Dim stu As stuEntities

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
stu= New stuEntities

stBindingSource.DataSource = stu.sts
End Sub
---------------------------------------------
Private Sub Addrecord_Click(sender As System.Object, e As System.EventArgs) Handles Addrecord.Click
stBindingSource.AddNew()
End Sub
-------------------------------------------------
Private Sub Saverecord_Click(sender As System.Object, e As System.EventArgs) Handles Saverecord.Click
stBindingSource.EndEdit
stu.SaveChanges(System.Data.Objects.SaveOptions.None)

End Sub

So ,first i click to "Addrecord" , and after i fill the 2 textbox , i click Saverecord.
The first record is saved with no problem.If a add another record , the record is saved , but when I open the table on database , the first record is saved 2 times , the second record is saved 1 time.
I try to add 3,4… records and everytime the last record is saved 1 time the others are all duplicated

If I call stu.SaveChanges() , with no parametres , I can’t add any records because I get an error :
The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager. Make sure that the key values are unique before calling AcceptChanges.
Please help me.

Thank you.

modified on Monday, August 29, 2011 9:41 PM

Hello!

I've got a piece of code where I need to parse a XML-file and store the data in a DataTable do modify and use the data from the file. I'm a bit stuck on the SelectNodes method.

If I have a XML file that looks like this:

XML

<?xml version="1.0" encoding="utf-8"?>
<MASTER.DATA>
    <Envelope>
        <MessageId>146413</MessageId>
        <MessageType>DataExport</MessageType>
        <Version>1.0.0</Version>
        <Sender>x4</Sender>
        <Created>2011-08-23T00:01:45.2367404+02:00</Created>
    </Envelope>
</MASTER.DATA>

The following code works like a charm:

VB

Dim xd As XmlDocument
Dim xnl As XmlNodeList

xd = New XmlDocument()
xd.Load(fileName)
xnl = xd.SelectNodes("/MASTER.DATA/Envelope")

BUT! The file doesn't exactly look like that. The MASTER.DATA actually looks like this:

HTML

<MASTER.DATA xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://nnnn.com/schemas/sys/1.0/integration IntegrationDocumentSchema.xsd" xmlns="http://nnnn.se/schemas/sys/1.0/integration">

And all of a sudden I don't get bupkis with the above mentioned code. What am I doing wrong?? Confused | :confused:

Any help is greatly appreciated. Smile | :)

//Jagg

Wexelblats algorithm:
Pick two: 1. Good, 2. Fast, 3. Cheap

I'm not sure whether the dot in the name of your rootnode is allowed. I'd go for a name without a dot.

XML

<MASTERDATA ..>
 (more stuff)
</MASTERDATA>

The query below should work;

VB

xnl = xd.SelectNodes("//MASTERDATA/Envelope")

Or, to get a specific piece;

VB

xnl = xd.SelectNodes("//MASTERDATA/Envelope[MessageId='146413']")

Hope this helps Smile | :)

Bastard Programmer from Hell Suspicious | :suss:

Hi, thanks for the reply.

However, that didn't work either. It works as soon as I remove all the other definitions (xmlns:xsi, xsi:schemaLocation and xmlns) from the MASTER.DATA (or MASTERDATA) but as soon as they are in the file it goes completely blank. I don't get any errors, I just don't find anything.

Regarding removing the dot (MASTER.DATA) it's probably not possible, this file gets sent automatically from one of our back end systems. Sigh | :sigh:

Wexelblats algorithm:
Pick two: 1. Good, 2. Fast, 3. Cheap

I have written a code to give a sliding effect to 5 command buttons. It runs fine with default background but when i change the opacity of the form OR put a picture in the background it behaves slower rather much slower than what it does normally. What might be the issue? Any ideas to resolve it. Here is the code.

VB

Public Class Form1
    Dim slidevar As Integer = -10
    Dim slidevar1 As Integer = -60
    Dim slidevar2 As Integer = -120
    Dim slidevar3 As Integer = -180
    Dim slidevar4 As Integer = -240
    Dim delayvar As Integer = -300
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Button1.Location = New Point(-1000, 10)
        Button2.Location = New Point(-1000, 80)
        Button3.Location = New Point(-1000, 120)
        Button4.Location = New Point(-1000, 160)
        Button5.Location = New Point(-1000, 200)
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

    End Sub

    Private Sub Button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button.Click
        slidevar = 0
        slidevar1 = 0
        slidevar2 = 0
        slidevar3 = 0
        slidevar4 = 0

        Button1.Location = New Point(-1000, 10)
        Button2.Location = New Point(-1000, 80)
        Button3.Location = New Point(-1000, 120)
        Button4.Location = New Point(-1000, 160)
        Button5.Location = New Point(-1000, 200)
        Timer1.Enabled = True


    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick


        If slidevar < 65 Then
            Button1.Location = New Point(slidevar, 10)
            slidevar += 6
            If slidevar4 > 65 Then
                Timer1.Enabled = False
            End If
        End If


        For delayvar = 1 To 100
        Next

        If slidevar1 < 65 Then
            Button2.Location = New Point(slidevar1, 80)
            slidevar1 += 5
        End If




        For delayvar = 1 To 100
        Next
        If slidevar2 < 65 Then
            Button3.Location = New Point(slidevar2, 120)
            slidevar2 += 4
        End If


        For delayvar = 1 To 100
        Next
        If slidevar3 < 65 Then
            Button4.Location = New Point(slidevar3, 160)
            slidevar3 += 3
        End If


        For delayvar = 1 To 100
        Next
        If slidevar4 < 65 Then
            Button5.Location = New Point(slidevar4, 200)
            slidevar4 += 2
        End If



    End Sub
End Class

you have already asked this question in QA[^]

What have you tried since then?

Lobster Thermidor aux crevettes with a Mornay sauce, served in a Provençale manner with shallots and aubergines, garnished with truffle pate, brandy and a fried egg on top and Spam - Monty Python Spam Sketch

Hello !
I'm starting to create a project with Vb.net 2010 and SQl server 2008r2.I don't know what to choose dataset or Entity framework ?

Another question :Are these both compatible with crystal reports ?

Thank you.

The two choices are not interchangable. You also haven't explained what you're app is going to be doing at all so it's impossible to say.

You're asking "Should I use these two bolts to build my project (DataSet)? Or use everything in this machine shop supply store (Entity Framework)?"

Neither of these has anything to do with Crystal Reports. CR gets its data from the database, not from the objects that make up and manage your data model.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

i try to create a data source on vb.net and there are 2 options : Dataset or Entity Data model ?
So how to decide which is the best choice ?
Someone can describe some avantages and disavantages on both model ?

What i'm going to do ? Usual things that someone can do with database :
Read , Write , Modify , Display , bound controls .... Sometimes with few records (50-10) , sometimes with much more (300-500)....
I read that if i choose one model i should continue with that , and can't use both models.
So what can i do ?

Thank you.

The "What are you going to do", was more a brief the application would be for.......

Lobster Thermidor aux crevettes with a Mornay sauce, served in a Provençale manner with shallots and aubergines, garnished with truffle pate, brandy and a fried egg on top and Spam - Monty Python Spam Sketch

this application would be for a school managment (student personal data , results, financial data...

OK, If you've never used either of these, don't even think of trying the Entity Framework.

Seriously, if you don't know what each of them is, you really don't have the skill set to use either of them. I highly suggest picking up a book on ADO.NET and/or Entity Framework 4.x and work through them. If you don't, you're just going to put yourself through an awful lot of pain and make bad design decisions that will cause your project to fail.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

thank you !
But i have create before a project using dataset.But i have read that entity framework is something new and better than dataset.And of course if entity framework is better than dataset , i will read some books before creating my project.
I want to know if possible some adavntages ( or disavantages ) of entity framework vs dataset ?

Or , if doesn't has importance what i know about both models , if a professionist have to choose : dataset or entity framework ? i like to know if possible your choice.
Thank you.

There is no "better". There is "appropriate".

What is appropriate for your application depends on your apps requirements, specifications and expected load. If you're doing this for a school project, I would probably suggest using the smaller dataset methods.

Serisouly, we know NOTHING of your application so you are the only one who can make this decision. But, in order to do that, YOU have to understand the capabilities and limitations, pros and cons of each. Pickup a book and start reading.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

ok. Can you suggest a book for beginners in entity framework ?
Thank you.

Pick onehttp://www.amazon.com/s/ref=nb_sb_ss_c_1_20?url=search-alias%3Dstripbooks&field-keywords=entity+framework+4.1&sprefix=entity+framework+4.1[^]

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

I have created a VB.NET app, a small mcq based quiz. Now when i run it on a different resolution than my PC then all the items(labels,textboxes etc) on the form get scattered.

How can we create resolution independent applications?

Windows Forms in .NET offers a great method variety of Autosizing, Docking and Align properties that should make it easier to get the positioning right for varying resolutions. You'll need to play around with them a bit to get a feel for it.
Alternatively, if these don't offer enough power, you'll need to write your own control-positioning/sizing code in the Resize event for the form.