Using VC# I've created a staff management app that, upon its first run, is expected to query the user for the path to a (.mdf) database which will reside on a remote computer. A resulting path may be something like
string dbPath = #"P:\remoteComputer\public\StaffTool\ExamplePersonnelDatabase.mdf";
Then I'm placing this string into a connection string template as so:
string dbConnectTemplate = #"Data Source=.\SQLEXPRESS;AttachDbFilename={0};Integrated Security=True;Connect Timeout=30;User Instance=True";
string dbConnectionString = String.Format(dbConnectionTemplate,dbPath);
Then I'm attempting to connect to the database LINQ to SQL style
ManagementDBDataContext db = new ManagementDBDataContext(
dbConnectionString);
At this point, an error pop's up stating that
The file "P:\remoteComputer\public\StaffTool\ExamplePersonnelDatabase.mdf" is on a network path that is not supported for database files.
An attempt to attach an auto-named database for file P:\remoteComputer\public\StaffTool\ExamplePersonnelDatabase.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
As I am relatively new to databases, I completely do not understand this message. And obviously, the file is not on a UNC share.
Any ideas?
Jim Lamb recommended that I connect to an instance of SQL server running remotely. Considering that I'm using LINQ to SQL, what refactoring do I have to do to make this happen? Other ideas still welcome - especially "push this button and everything will work" solutions.
Another clue: A coworker said that there used to be some way to work through Control Panel->Administrative Tools->Data Sources(ODBC) so that a remote database could be viewed from my computer as if it was local. The coworker didn't know any more details besides this.
You are attempting to connect to a database file on another machine over a network connection, which isn't supported by SQL Express. You'll need to make a local copy and attach to that, or connect to an instance of SQL that's running on the same machine as the MDF file.
Related
I have a simple data entry Windows Form with a datagridview display that links to a local database. When I run the program and try to add data on another computer, I get this message:
Unhandled exception has occurred in your application. If you click Continue, the application will ignore this error and attempt to continue. If you click Quit, the application will close immediately.
An attempt to attach an auto-named database for file C:\Users\roberto.yepez\Documents\Visual Studio\2010\Projects\Financial Aid Calculator\Financial Aid Calculator\StudentInfo1.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share."
The file path is to the path on the computer where I coded the program.
Here is my code:
SqlConnection conn = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename='C:\Users\roberto.yepez\Documents\Visual Studio 2010\Projects\Financial Aid Calculator\Financial Aid Calculator\StudentInfo1.mdf';Integrated Security=True".ToString());
I am a self-taught coder, please help! :)
I believe you're running into a problem because your local sql server to which your code is trying to attach the StudentInfo1.mdf (whose path is in the connection string) already contains a database called StudentInfo1 - it decided to try and create a database of this name based on the name of the mdf file. I'm guessing that you can pick your own name by specifying Initial Catalog in your connection string but this would mean there are two databases with possibly the same set of tables and a potential for confusion
Per the comment I posted I would instead advocate that you use SQL Server Management Studio to permanently attach your db (you make have already done this) and then adjust your connection string so that it refers to the permanently attached db. This reduces the chances that your next question will be "my code says it's updating my db but I cannot see any changes!?"
Please move this connection string
"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename='C:\Users\roberto.yepez\Documents\Visual Studio 2010\Projects\Financial Aid Calculator\Financial Aid Calculator\StudentInfo1.mdf';Integrated Security=True"
to app.config file. When you deploy to production, change the paths in that app.config, according to the production machine settings.
You can even apply transformations on the app.config to deploy in various machines/scenarios.
I'm writing a portable program that can be used on other computers as well as mine and It also connects to the SQL Database on that computer.
So the problem is that I don't have the database name of that computer. How can my program connect to that Database without previously knowing the database name?
In other words, I don't have enough information to create a complete ConnectionString.
Connect to SQL Server's master database first.
Then, using this query, you can get data from databases in your database:
SELECT name FROM master.dbo.sysdatabases
Using the site below, you can find the right Connection strings for you :
https://www.connectionstrings.com/
You can use a dot in the connection string to represent.tbe local server.
Create a txt file, rename the extension to UDL. Open the UDL file and put a dot, a full stop:
If you have installed a SQL Instance (ie not the default instance) it will be .\InstanceName
Choose the Database drop down and click Test Connect.
Finally close the URL file and open it with NotePad and you will see the connection string.
My application does basic CRUD operations over an external .mdf file. The database file is created separately in SSMS. On my PC, everything works perfectly fine. When I install it on someone else's computer, it refuses to connect to the database. The other PC also has the same database at the exact same location.
The connection string I am using is (in app.config):
conString=Data Source =.\sqlexpress; Initial Catalog = dbName;
Integrated Security = True; Pooling = False
In my code:
dbConnection = new SqlConnection(Settings.Default.conString);
The other PC has SQL Server installed as well. Tried going through almost all the results but almost all of them suggest either
Adding the existing database with the project. I can't seem to do that because when I try that I get an error:
permission denied
I can't rewrite the whole code with a service based database pre-attached to it.
I've got this scenario: I developed a C# application which connect to a mdb file (Access 2003) through OleDBConnection (engine = Microsoft.Jet.OLEDB.4.0). This mdb file has some linked tables in another mdb file in the same directory. Everything works perfectly in the local environment, the query retrieves data from linked table even if I connect only the main mdb file. A simplified schema could be:
my application in the local machine --> C:\mydir\main.mdb --> C:\mydir\linked_tables.mdb
But this application should work in some host computers of a local network. And the mdb files are stored in a server in a shared directory. Well, when the application is running in a host I set the path as follow:
\\myserver\mydir\main.mdb
The connection works. The problem happens when I launch a query which tries to get data from linked tables. It tries to find the linked table in C:\mydir\linked_tables.mdb, but this path is on the server, not in the host.
Is there a way to tell him: if the path of the main mdb file is \\myserver\mydir\main.mdb you must (automatically) get the linked tables on \\myserver\mydir\linked_tables.mdb?
Thank you
I solved with another connection. I mean: for each mdb file I use a different OleDBConnection.
OleDbConnection MainConn = new OleDbConnection("\\myserver\mydir\main.mdb");
OleDbConnection LinkedTablesConn = new OleDbConnection("\\myserver\mydir\linked_tables.mdb");
Not so elegant, but it works. If I have to do some join of tables located in different databases, I manage them with some generic collection objects.
newbie here.
I have a local db in my program. Whilst I was developing the program I used the SQL
Connection string :
SqlConnection sconn = new SqlConnection(#"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\leemk_000\Documents\......Integrated Security=True;User Instance=True;");
Now If I want to load this program onto a different computer I am sure that this connection will no longer work simply because it will still be looking for Users\Lee_000\
I have tried to remove Lee_000 but I get this following error:
An attempt to attach an auto-named database for file C:\Users\Documents..... failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
What can I do to get a connection string to work on different computers.
With many thanks
The whole User Instance and AttachDbFileName= approach is flawed - at best - especially when you want to share your database amongst multiple clients!
When running your app in Visual Studio, it will be copying around the .mdf file (from your App_Data directory to the output directory - typically .\bin\debug - where you app runs) and most likely, your INSERT works just fine - but you're just looking at the wrong .mdf file in the end!
If you want to stick with this approach, then try putting a breakpoint on the myConnection.Close() call - and then inspect the .mdf file with SQL Server Mgmt Studio Express - I'm almost certain your data is there.
The real solution in my opinion would be to
install SQL Server Express (and you've already done that anyway)
install SQL Server Management Studio Express
create your database in SSMS Express, give it a logical name (e.g. YourDatabase)
connect to it using its logical database name (given when you create it on the server) - and don't mess around with physical database files and user instances. In that case, your connection string would be something like:
Data Source=.\\SQLEXPRESS;Database=YourDatabase;Integrated Security=True
and everything else is exactly the same as before...
If it's a local db you should be placing it within the app folder and carry it with the app right?
Put the database in the App_data folder of your app and use that in your connection string
<add name="YourConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\yourfile.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>
You need to use a database server and let your users use it via your connection string like this;
Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;
"myServerAddress" should be the ip adress of your server machine.