Access Database Design and Programming, Second Edition

The ODBC Driver Manager

The purpose of the ODBC Driver Manager is to manage communication between the application and the driver. The application communicates directly with the Driver Manager, which in turn either processes the command or sends it on (with or without some modification) to the driver. (It is possible for an application to communicate directly with a driver, but this is not usual.)

Generally, the Driver Manager just passes API function calls from the application to the correct driver. However, it does implement some API functions and also performs some basic error checking. In particular, it is responsible for implementing the following driver/data source information functions:

• SQLDataSources: Returns information about a data source.

• SQLDrivers: Lists driver descriptions and attributes.

• SQLGetFunctions: Determines whether a given driver supports a given ODBC function.

The Driver Manager is also responsible for managing the connection to and disconnection from an ODBC driver. In particular, when an application wants to use a particular driver, the application calls one of the following connection functions:

• SQLConnect: Establishes a connection to a driver and a data source.

• SQLDriverConnect: Establishes a connection using a connection string.

• SQLDriverBrowse: Establishes a connection iteratively.

Each of these functions must include information about the driver in its parameters (in different forms, however). Using this driver information, the Driver Manager loads the driver ...