•
•
•
•
What is DaniWeb IT Discussion Community?
You're currently browsing the VB.NET section within the Software Development category of DaniWeb, a massive community of 373,096 software developers, web developers, Internet marketers, and tech gurus who are all enthusiastic about making contacts, networking, and learning from each other. In fact, there are 3,945 IT professionals currently interacting right now! Registration is free, only takes a minute and lets you enjoy all of the interactive features of the site.
Please support our VB.NET advertiser:
Views: 2205 | Replies: 5 | Solved
![]() |
Through using Visual Studio to learn more about ASP.net and VB.net I would like to connect to a database. I create an .mdf database file but I've no idea how to connect to it (well, I have some code below...) that's not my only problem but I'll ask the next question in a moment. The code I'm using is shown below, am I missing something? Or using the wrong connection string?
A similar connection string works (
Secondly as you can see I've got the function set as a Boolean, however I don't return anything and the .Open() function doesn't return anything. Therefore how can I check to see whether a connection is succesful or not before it breaks out into an error? I'd like to be able to catch it just incase.
Thanks for your time.
VBNET Syntax (Toggle Plain Text)
Private Function sqlDBConnection() As Boolean 'Set the variables Dim SQLConnectionString As String Dim SQLConnection As New SqlConnection() 'Create the Connection String SQLConnectionString = "Data Source=.\SQLEXPRESS;AttachDbFilename=\App_Data\Overland.mdf;Initial Catalog=Overland;Integrated Security=True;User Instance=True" 'Set the connection string into the SQL connection SQLConnection.ConnectionString = SQLConnectionString 'Open up the connection SQLConnection.Open() End Function
A similar connection string works (
"Data Source=LAMBDA\SQLEXPRESS;Initial Catalog=General;Integrated Security=True") with an actual database server (SQL Express 2005) but modifying it a bit doesn't work for an SQL Server file (.mdf in this case) so if you have any idea please help 
Secondly as you can see I've got the function set as a Boolean, however I don't return anything and the .Open() function doesn't return anything. Therefore how can I check to see whether a connection is succesful or not before it breaks out into an error? I'd like to be able to catch it just incase.
Thanks for your time.
Stone In Focus - Caffeine Group - CoffeePHP - Open Notes - Onyx - Redpoint Network - Espresso
•
•
Join Date: Mar 2008
Posts: 6
Reputation:
Rep Power: 0
Solved Threads: 1
•
•
•
•
Through using Visual Studio to learn more about ASP.net and VB.net I would like to connect to a database. I create an .mdf database file but I've no idea how to connect to it (well, I have some code below...) that's not my only problem but I'll ask the next question in a moment. The code I'm using is shown below, am I missing something? Or using the wrong connection string?
VBNET Syntax (Toggle Plain Text)
Private Function sqlDBConnection() As Boolean 'Set the variables Dim SQLConnectionString As String Dim SQLConnection As New SqlConnection() 'Create the Connection String SQLConnectionString = "Data Source=.\SQLEXPRESS;AttachDbFilename=\App_Data\Overland.mdf;Initial Catalog=Overland;Integrated Security=True;User Instance=True" 'Set the connection string into the SQL connection SQLConnection.ConnectionString = SQLConnectionString 'Open up the connection SQLConnection.Open() End Function
A similar connection string works ("Data Source=LAMBDA\SQLEXPRESS;Initial Catalog=General;Integrated Security=True") with an actual database server (SQL Express 2005) but modifying it a bit doesn't work for an SQL Server file (.mdf in this case) so if you have any idea please help
Secondly as you can see I've got the function set as a Boolean, however I don't return anything and the .Open() function doesn't return anything. Therefore how can I check to see whether a connection is succesful or not before it breaks out into an error? I'd like to be able to catch it just incase.
Thanks for your time.
You cannot directly 'Open' and .mdf file with Vb.NEt. You need to you an SQL server or MSDE. The second connection string you mention appears to connect to an SQL server, hence why it works.
As to your second question, If you are looking to catch exceptions, use the Try Catch method as demontrated below:
Try SQLConnection.Open() Catch Ex As System.Exception MsgBox(ex.Message, MsgBoxStyle.Critical, "Error Information") End Try
If you are looking to obtain the state of an SQL connection before you open it you can use this if statement:
If sqlConnection.State = ConnectionState.Closed Then
sqlConnection.Open()
End IfHope this helps.
Green2Go
Last edited by green2go : Mar 25th, 2008 at 6:02 pm. Reason: Typo :P
If I can't directly open the .mdf file how can I access it? It's just something I'm looking into since I've no idea what it is compared to an actual database on a SQL server :/
Thank you so much with the Try/Catch method, I had seen it once or twice before in PHP but it's not used much by the people I speak to but it seems to come in useful in VB.net thanks
and the second part will be useful to, saving me opening up multiple unneeded connections. thanks
Thank you so much with the Try/Catch method, I had seen it once or twice before in PHP but it's not used much by the people I speak to but it seems to come in useful in VB.net thanks
and the second part will be useful to, saving me opening up multiple unneeded connections. thanks
Stone In Focus - Caffeine Group - CoffeePHP - Open Notes - Onyx - Redpoint Network - Espresso
•
•
Join Date: Mar 2008
Posts: 6
Reputation:
Rep Power: 0
Solved Threads: 1
No problems for previous comment. You need to have an instance of SQL server express (http://msdn2.microsoft.com/en-gb/express/bb410792.aspx) free from Microsoft running on your local machine if you can't access an SQL server already setup on a network and/or are planning to deploy the application to locations without access to a server.
You then use a connection string to connect to the SQL server instance and read, write and query the data as you are already. See this link for connection strings for SQL Server 2005(http://www.connectionstrings.com/?carrier=sqlserver2005)
You can mount database files (.MDF) and other handy stuff using these commands.
Other than using a full blown server you could use an Access database to store the data, if there isn't lots of it, all that it requires is the correct drivers which I think are standard on most windows based machines anyway. You would have to convert the data from the SQL Server MDF file into an Access MDB file.
Green2Go
You then use a connection string to connect to the SQL server instance and read, write and query the data as you are already. See this link for connection strings for SQL Server 2005(http://www.connectionstrings.com/?carrier=sqlserver2005)
You can mount database files (.MDF) and other handy stuff using these commands.
Other than using a full blown server you could use an Access database to store the data, if there isn't lots of it, all that it requires is the correct drivers which I think are standard on most windows based machines anyway. You would have to convert the data from the SQL Server MDF file into an Access MDB file.
Green2Go
Last edited by green2go : Mar 25th, 2008 at 7:13 pm.
Thank you for your time and help, after some fiddling and with that site I managed to open up the database file, now I'm going to test whether I can run SQL queries on it and such. Thanks once again, I'll keep that site bookmarked
Stone In Focus - Caffeine Group - CoffeePHP - Open Notes - Onyx - Redpoint Network - Espresso
![]() |
•
•
•
•
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
•
•
•
•
•
•
•
•
DaniWeb VB.NET Marketplace
•
•
•
•
age amd avatar backup blue gene breach business chips daniweb data data protection database development dos economy energy enterprise europe government hacker hardware hp ibm ibm. news intel ibm it linux medicine memory microsoft news open source openoffice pc ps3 recession red hat russia security server sql sun supercomputer supercomputing survey technology trends ubuntu working x86
- Updated : Simple ASP.Net Login Page (ASP.NET)
- Create Database Connection in the C#.net (C#)
- connecting to Data.SqlClient (ASP.NET)
- Beginner: Insert, Update, Delete & Search records from/to sql database (ASP.NET)
Other Threads in the VB.NET Forum
- Previous Thread: Date serial command dates
- Next Thread: getting killed by word 10.0 object library


Linear Mode