How do I create a generic file path to a local database in a C# Application?

Question

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! :)

Before you go any further, take a read of sentryone.com/blog/aaronbertrand/bad-habits-attachdbfilename — Caius Jard
– Caius Jard, Commented Apr 26, 2020 at 6:25

Caius Jard · Accepted Answer · 2020-04-26 06:30:48Z

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!?"

user10902438 · Accepted Answer · 2020-04-26 13:06:37Z

0

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.

answered Apr 26, 2020 at 13:06

user10902438

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