# Database: ODBC: Defining Data Source

## ODBC

ODBC (Open DataBase Connectivity) is a protocol for communicating SQL commands with databases. Most database systems support ODBC in addition to their their own, native, interface. While ODBC is usually the lowest common denominator, it is adequate for most database operations.

## Client Interfaces

The database engine may be located on one machine, and the client interface may be located on another. Microsoft Access has both a database engine and a client interface, and either can be used independently. For example, the Access client interface can be connected to other database engines (eg, Oracle, MySQL, PostgreSQL, ...) over the Internet, and other clients can be connected to the Access database engine.

## Defining a Data Source Name (DSN) for other clients

If you want to use an Access database from another client on the same machine, eg WinSQL, you need to create a new data source name for the client to make an ODBC connection to.

- Open the ODBC control panel (Start > Settings > ODBC).
- In the User DSN tab, click Add.
- In the dialog that comes up, create a name for the data source, and select the database you want to make available, and click OK.
- Close the ODBC dialog box with OK.
There are lots of other data source options, but it's simple to make a data source that can be used on your machine.

## Using the Data Source from another client

To use this from WinSQL:

- Start WinSQL.
- Choose the Data Source you want to use. You can now inspect the tables and issue SQL commands from WinSQL for your Access database. Note that Access doesn't even have to be running. The Access ODBC drivers were specified with the DSN, so these are used to start the Access database engine.