Terminology » Networking Basics » DSN vs DSN-less vs UDL: Understanding Database Connection Methods

DSN vs DSN-less vs UDL: Understanding Database Connection Methods

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This article explains the differences between various types of Data Source Names (DSN), DSN-less connections, and Universal Data Links (UDL).

Introduction

DSN stands for Data Source Name. It’s a data structure containing database connection information, essentially what’s needed to connect to a database. The common DSN types are file DSN, system DSN, and user DSN.

UDL stands for Universal Data Link, also known as a Microsoft Data Link. It’s a universal file that contains database connection information.

Different database drivers offer various ways to establish a connection. The following sections describe common techniques used to interact with database providers.

System DSNs

  • Accessible by anyone with system access.
  • Storage: Stored in the local machine section of the system registry.
  • Example: Visible to all users who log into the machine.

User DSNs

  • Specific to a user on the machine.
  • Storage: Current user section of the system registry.
  • Behavior: A User DSN is only visible to the user who created it, not to others logging into the same machine.

File DSNs

  • Can be stored on disk or on a network.
  • Usable on any machine that has access to the file.
  • Storage: Stored in a file, not the registry.
  • Accessibility: Any user with file access can utilize the File DSN.

UDLs

  • NI’s (National Instruments’) database toolkit often uses OLE DB to communicate with databases.
  • With DSNs, commands are translated from OLE DB to ODBC via the OLE DB provider for ODBC.
  • Recommendation: Using UDLs as the connection method with the toolkit is more efficient (when an OLE DB provider is available for the database).

DSN-less

  • Doesn’t require a DSN to store connection information.
  • Storage: Registry, INI file, table, etc.
  • Mechanism: The user is prompted for connection details at runtime, or the details are retrieved from the storage medium.
  • Example: SQL Query Analyzer

DSN Types Summary

The following table summarizes the DSN types discussed above:

DSN types

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