I built a program using cBuilder, with an oleAuto interface to allow some client to make some simple query to the server com.
I want to close the server when for some reason ( ex. the db connection is lost ) something is wrong and a I need to restart the server.
The problem is that if there are some clients connected through the COM reference I get a dialog that prompt me to confirm that I want to close this application.
Is there some way to avoid the dialog and force the closing of the server?
Well obviously you need to release all references to the object in order to properly close the server.
Were you unaware of that, or is there a reason why you need to hold on to the reference?
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I am coming from a php background background where we remotely connect to the database and manipulate everything with php code. Now in vb.net, will the performance of my desktop application be affected in anyway if i connect manually in the form_load event event instead of vb.net database source connection?
i come from both backgrounds.
yes you can manually open database BUT
you should specify the database you are using to make the best performance in your desktop application, for example:
in access database (mdb files), you should open the database once in form_load, and use it all the time, then close it before exitting the application in form_closing (this is for better performance)
while in SQL Server, you should open the database for each function then do your queries then close it after you finish.
Create a DataAccessClass.
Do your db functions in this class (update functions, select functions etc)
Connect to the db on class instantiation.
give your class the necessary work to do, and receive answers back from the class.
In essence, extract your data access from your forms, so that you can reuse your data class anywhere in your app
My application (a testcase automation tool) does not support calling ODBC's SQLSetStatmentOption. I need to set the cursor option SQL_SOPT_SS_CURSOR_OPTIONS to SQL_CO_FFO_AF. Right now I connect to the server using a connection string (no DSN). I am using sqlsrv32.dll or Sqlncl10.dll.
Is there a way to set the cursor option in a DSN (or other layer) between my tool and the MSSQL server? The tool handles creating the cursor (or results set) and iterating through the result set in a way that seems to obscure any ability to manage it directly. It does allow for calling SQLSetConnectAttr() but as far as I can tell there's no way to set a cursor option in there.
All of this is an attempt to speed up retrieving data over a remote connection. In SQL Management Studio I get comparable response times to the local or remote DB, but in the automation tool the remote queries take hundreds of times longer, probably because it seems to be making a round trip to the sever for every row.
There is no way to set statement options in the connection string that I know of. In ODBC 1.0 and 2.0 you could make calls to SQLSetConnectOption for statement attributes and they set those attributes in each statement created in that connection but a) that is an old version of the API (although it probably still works) b) you still cannot do it from the DSN. In unixODBC you can set some environment and connection attributes in the DSN but your obviously Windows.
I'm not convinced anyway that you've identified the problem correctly and even if you have, how do you know your app does not use SQLGetData (which is disabled when you set SQL_CO_FFO_AF). Are you sure you've not enabled MARs. Did you try getting an ODBC trace to see what the app is doing?
I want to create a global connection class from Sql server database to vb.net to make it easy in later editing the connection. Could anyone guide me the way to code both creating and calling to individual form?
Any help would be appreciated. Thanks
Keep your connection string in your web.config file. (this gives you a single point where you can change the connection string without needing to recompile your application, it also allows you to encrypt it in the future to protect your DB server).
I'd advise against using a single "connection" object for reuse. Open and close a connection for each query or transaction.
Check out the Repository pattern instead. http://msdn.microsoft.com/en-us/library/ff649690.aspx
I am here to write a small database application that will be running in desktop (offline mode).
I am using MSAccess 2007 as my database file and trying to write code in vb.net.
I used to write the code vb6 an usually had global variables for storing database connection and executing every query from that.
I am trying to upgrade myself from vb6 to vb.net.
do i need to read some more simple starter books also?
In .NET, talking to a database is handled with ADO.NET, which uses something called "connection pooling". The connection pool is basically a collection of open connections to your database that ADO.NET manages for you. In your code, when you create and open a Connection object, ADO.NET first looks in the connection pool to see if it already has an open connection to your data source, and if it finds one it uses that (instead of actually creating and opening a new connection). When you close your connection, ADO.NET does not really close it, but instead returns it to the connection pool.
Therefore, you do not need (and in face do not want) to maintain open connection objects inside your application (in a global variable or anywhere). The correct approach with data access in ADO.NET is to create and Open a Connection object, do whatever you need to do with the database, and then Close and Dispose your Connection.
Store the connection string in the config file (in the solution explorer, open the My Project folder and doubleclick on Settings.settings).
I'd suggest that you create one or more classes to contain your database code and let those classes convert between the database data and your application objects, most VB6 projects I saw had the GUI hard linked to the DB which can make future maintenance or new features very difficult and limits the possiblity of code reuse.
If you've got VB6 experience I'd thought that you could probably start trying to create the application right away but you should definitely read either a good book or good articles about it at the same time so that you pick up things like that you need to Dispose of your database objects after user etc.
It's probably a good idea to get a book, a lot has changed since VB6.
Also consider using a more robust db, like SQL compact or SQLite. It will allow you you use the Entity Framework which will make writing your app a whole lot easier.
I'm working on a program that needs to edit some objects in an Access database. It also runs a subprogram (long story) that tries to access the underlying JET database while Access still has it open via ODBC.
The problem is that as soon as I start editing Form objects using VBA - for example, using Application.LoadFromText - Access changes the database to exclusive mode. Exclusive mode itself is fine, and I know why it needs it. But I need to be able to switch back to "shared" mode afterwards so that I can run my subprogram.
I've observed that if you use the UI to open a Form in Design mode, Access switches the database to Exclusive. (You can confirm this by trying to open it from another computer.) But when you then close the form designer, Access immediately switches it back to shared mode, which is what I would hope for.
Is there a way to switch it back and forth myself using VBA / COM calls?
I know I can call Application.CloseCurrentDatabase() followed by OpenCurrentDatabase(), but that closes all the windows and upsets the UI, so it's not ideal.
Is splitting the database into a separate front-end with the forms/modules/etc. and back-end with the tables an option? That way if the front-end is locked, the back-end is still accessible. Access has a database splitting wizard for just that.
You might try .UserControl and .Visible. I use them to transfer control in automated processes.