How to Connect oracle database using C#.
Please take a look at this site:
Also you can right click on your desktop and click New and then select text document. Call the file test.udl (it will ask if you are sure you want to change the file extension, click yes). You can now double click the udl file and fill in your database parameters. Once you have tested your connection you can open that file in notepad and the last line is your connection string.