Data source name (DSN) is a data structure that contains information about a database. The information is needed in order to connect to the database. A Universal Data Link (UDL, also known as a Microsoft Data Link) is a universal file that links to a database.
There are many different database drivers (or providers) with many ways of connecting to them. The table below list the five most common ways in which you can interact with a database provider.
|Connection Method||Who Can Access Them?||Where Connection Information is Stored|
|File DSN||Any user who has access to the File||In a file format (*.dsn)|
|System DSN|| Any user on that system||System Registry|
|User DSN||Only for the user for which that data source was created||System Registry|
|UDL (Universal Data Link)||Any user who has access to the File||In a file format (*.udl)|
|DSN-less||Any one who has access to the database files (i.e. mdb,.xls)||No static storage of connection information (passed as the connection string during runtime)|