VB.NET P2P application? - Visual Basic Discussion Boards

i am creating a backup programme. My Question is that when i copy a folder to another location and if the folder is already exist then it should overwrites only those folders whose modifed date is older than today. so please tell me how can do this. Anyone have codes........ Sniff | :^)

Thank you
Dharmendra

The easiest solution is to compare dates.

Hi,
I am using Crystal Reports with .NET 2.0 for generating reports in my project. My database is SQLSERVER 2000.
I want to display list of absentees between 2 given dates.
For this I have written a stored procedure like below.

CREATE procedure tesk4(@Fromdate DATETIME, @Todate DATETIME)
as
declare
@return BIT

WHILE @Fromdate <= @Todate
BEGIN

SET @Fromdate = @Fromdate + 1

if DATENAME(WEEKDAY, @Fromdate) IN ('saturday', 'sunday')
print'saturday'
else
if @Fromdate IN (select holdate from holidays )
print 'Holiday '
else
select card_no from carddata where card_no Not in(select card_no from swipes where sdate =@Fromdate)

END
GO

Now how call this procedure in report as it have parameters.

Pls help me with a solution for this problem

You can do it directly in CR but it's tricky and a pain.
Better insert a DataSet into your project and there add a TableAdapter for your stored Procedure (easy - you get an nice assistent).

After this add a crystal report document to your project and set it's database to this dataset.

Finally you only have to set the DataSource of the report to the DataTable returned by the DataAdapter before showing/printing.

Thanks a lot for your instant reply
I have no idea about Report Document.
Help me to get a clear idea on Report Document
otherwise
doing it directly in CR which you said Tricky

Hi,

We have a situation where we need to 'move' a file from one location to another. We are using the moveTo method of fileInfo class for this. But the issue with this is that when we execute it, the file, after it has been moved to the destination folder retains the previleges of the source folder whereas it should have gotten the previleges of the destination folder. copyTo method of the same object does not have this problem.

One alternative is to use the copyTo method and then delete method but that becomes a little risky and we do not want to go that route.

Any ideas how we could acheve 'moving' a file in VB.NET without using the fileInfo.moveTo()?

Responses will be greatly appreciated.

Thanks
sb_

Moving a file WILL retain the permissions set on it specifically. It will not retain what it inherited from it's parent folders.

Copying will avoid this situation since you're creating a new file in the new location. The new file will inherit all of the permissions of the destination's parent folders, subject to the user's security permissions too.

If you want to move the file without the permissions, you can copy the file to the new location, then delete the original.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

Hi,

As the title says I need an code sample for direct connection between two devices (computers, or something else( in this case windows CE device)) when one of them connects to the other it directly sends some file (over the internet, using IP address and port) I have tried using TcpClient and tcpListener But I can't get it to work. my code:

The function that listens for a connection:

Const portNumber As Integer = 8000
Dim tcpListener As New TcpListener(portNumber)

tcpListener.Start()
Console.WriteLine("Waiting for connection...")
Try
'Accept the pending client connection and return a Tcplient initialized for communication.
Dim tcpClient As TcpClient = tcpListener.AcceptTcpClient
Console.WriteLine("Connection accepted.")
' Get the stream
Dim networkStream As NetworkStream = tcpClient.GetStream()
' Read the stream into a byte array
Dim bytes(tcpClient.ReceiveBufferSize) As Byte
networkStream.Read(bytes, 0, CInt(tcpClient.ReceiveBufferSize))
' Return the data received from the client to the console.
Dim clientdata As String = Encoding.ASCII.GetString(bytes)
Console.WriteLine(("Client sent: " + clientdata))
Dim responseString As String = "Connected to server."
Dim sendBytes As [Byte]() = Encoding.ASCII.GetBytes(responseString)
networkStream.Write(sendBytes, 0, sendBytes.Length)
Console.WriteLine(("Message Sent /> : " + responseString))
'Any communication with the remote client using the TcpClient can go here.
'Close TcpListener and TcpClient.
tcpClient.Close()
tcpListener.Stop()
Console.WriteLine("exit")
Catch e As Exception
Console.WriteLine(e.ToString())
End Try

The function that connects to the other device and sends the file:

Dim tcp As New System.Net.Sockets.TcpClient()

tcp.Connect(Me.tcpIPAdresa, Me.brojPorta)
Dim nStream As NetworkStream = tcp.GetStream
If nStream.CanRead And nStream.CanWrite Then
Dim sendBytes() As Byte = Encoding.ASCII.GetBytes("microstar")
nStream.Write(sendBytes, 0, sendBytes.Length)
Dim bytes(tcp.ReceiveBufferSize) As Byte
nStream.Read(bytes, 0, CInt(tcp.ReceiveBufferSize))

Return True

Else
If Not nStream.CanRead Then
MsgBox("error cannot write")
tcp.Close()
Return False
Else
If Not nStream.CanWrite Then
MsgBox("error: cannot read data from the stream")
tcp.Close()
Return False
End If
End If
End If

Any ideas, code samples, anything.

Help greatly appreciated!

Fist: do you get the "Connection accepted" message?
If not your "Me.tcpIPAdresa" of "Me.brojPorta" might be wrong.

Second: please state what you've allready tried, what your steps where, test runs etc. - just posting a (not stand-alone) codeblock and beging for help will not work without further info.

Examples you will find in the MSDN documentation to TcpListener

Hello,

I am trying to come up with a way of securing controls inside of a VB.NET 2005 application (Window form). I have searched and found information but the resources seems to be all based on ASP.NET (Codeproject's article are also not useful enough, like http://www.codeproject.com/KB/vb/2gs_txtbx.aspx#add[^])

I have created database to store values for username and password. I have already did a user login which verify the username and password. I want to have two level levels of security. One that has limited access to certain forms(users) and another that has full access(admin). I want one user to be able to access a screen with controls such as data grid view but not be able to edit them. Is there any good concepts out there on how to manage this efficiently? Any help would be greatly appreciated.

Thanks,
telly

I tried to declare functions of DLL file in project directory with VB 2005/2008. However, I need to specify file path of DLL. Otherwise, VB cannot find DLL file when calling the function. Is there any other way I can make project directory default when loading DLL?

Current code:

Public Declare Auto Function CmodConnect Lib "C:\Visual Studio 2008\Projects\Cmod\Cmod.dll" _
(ByVal Address As Integer) As Boolean

Change to:

Public Declare Auto Function CmodConnect Lib "Cmod.dll" _
(ByVal Address As Integer) As Boolean

ADd the path to the PATH variable on your computer. But, really, the dll should just be local, that's the best way to do it.

Christian Graus - Microsoft MVP - C++

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

The DLL file is not a COM or assembly component. Thus, I could not use "Add Reference". The PATH might cause problem when moving to other computers. Is there other way to force VB to link the DLL file?

Thank you,

Steven

bj93081 wrote:
The PATH might cause problem when moving to other computers

Absolutely - for deployment, the dll needs to be in the same folder as the exe, or a subfolder which you specify. That's kind of why I said that's the best way to go. Why would you want to put it elsewhere ?

Christian Graus - Microsoft MVP - C++

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

hi,
i use windows application I want validation to create texbox write arabic only
please send to me a sa
mple code

Ahmed hassan

You want your windows app textbox to accept only arabic characters ? I guess you need to work out their range in Unicode, and then handle the keypress event to reject keys not in that range.

Christian Graus - Microsoft MVP - C++

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

Not sure if I can help but you might want to google a bit.

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

hi all,

i have a System DSN connection where i have to create an exe to check a particular table in the database with some status.

can any body let me know.

thanks in advance

M.MohanVamsi

What have you tried ? Do you use google to look for information ?

Christian Graus - Microsoft MVP - C++

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

i tried to look into google but i'm not getting proper stuff.

i already have a system dsn.

just i want to connect with visual basic and run some query on the tables

can you please let me know how to connect.

M.MohanVamsi

Do you have a connection string ?

Christian Graus - Microsoft MVP - C++

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

I suggest that you follow this tutorial through from the beginning.
The end of the tutorial introduces databases:
Clicketty

You always pass failure on the way to success.

Hello. I designed a scheduling application for my office in Visual Basic 2005 Express. It connects intermittently to an MS Access mdb database (on our office share drive) to populate datasets and make changes and updates to tables in the database. Occasionally it is used my multiple users at once but most of the time it is used by one user at a time. What baffles me is that I get concurrency exceptions even with one user. (As I had previously understood it - obviously incorrectly - concurrency errors were caused by two users trying to change the same row of data at the same time.) I'd really like to get to the root of what's causing these errors. It's not enough for me to Try - Catch these errors and display a messagebox; I'd like to understand what's causing the errors and handle them more intelligently.

In general, what could be causing single user concurrency errors? How can I effectively search for the cause of the errors? (It seems that they occur at very random times.) Any advice from someone who knows more about concurrency than me (or where could I learn more)? Thanks, all.

Regards,

Craig

"That rug really tied the room together."

modified on Thursday, December 20, 2007 12:05:22 PM

craigmg78 wrote:
As I had previously understood it - obviously incorrectly - concurrency errors were caused by two users trying to change the same row of data at the same time.)

That's true - you got that wrong. A concurrency failure occurs when an application goes to update a row in a database and the data in that row has changed since the application read the row OR the application made a mistake in identifying the row to be updated. For instance, when your application gets a row from the database, it sees something like:

ID  FirstName  LastName   PhoneNumber
 1   Joe        Schmoe      555-1212

Say you are trying to change the phone number. You make the change in the application and the app is trying to write the new data back to database. Well, id order to identify the record, the code is using an SQL query that looks something like this:

UPDATE ContactsTable
SET FirstName = 'Joe', LastName = 'Schmoe', PhoneNumber = '123-4567'
WHERE ID = 1 AND FirstName = 'Joe' AND LastName = 'Schmoe' AND PhoneNumber = '555-1212'

Notice that the WHERE clause in the SQL statement mentions all the fields in the table and gives the values of the fields as they are supposed to be now, when the application read this record. This is how the code matches up the record it intends to update with the record in the table. If any of these fields do not match, the record is not found, and hence cannot be updated. The "number of rows affected" by this SQL statement should return 1 if the change is successfully written.

If the "number of rows affected" comes back 0, or greater than 1, this throws the concurrency exception in your code. Now, what are the possible causes of "rows affected" returning a non-1 value?

1) The record in the database has been changed by an outside source. This is either another user updated the same record, the database changed the record in response to some other application, or some problem with the database.

2) The data in the WHERE clause of the SQL UPDATE statement is not correct. What the application read before is not what the app is now submitting in the WHERE clause to uniquely identify this record.

For example, your application read the record in the example above (1, Joe, Schmoe, 555-1212), but, for some reason, when it build the SQL statement to update the record with new data, the data it used in the WHERE clause doesn't match what it read. It might be doing something like:

UPDATE ContactsTable
SET FirstName = 'Joe', LastName = 'Schmoe', PhoneNumber = '123-4567'
WHERE ID = 4 AND FirstName = 'Frank' AND LastName = 'Schmoe' AND PhoneNumber = '555-1212'

Notice the ID and FirstName fields in the WHERE clause no longer match what was originally read. This too can cause a concurrency violation, without another user using the database.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

modified on Thursday, December 20, 2007 2:01:13 PM

That has given me some real food for thought. Now I just have to hunt for cases in my code where I have done something like you mentioned! Thank you for your detailed response.

- Craig

"That rug really tied the room together."