ODBC Driver Architecture
Driver writers must be aware that the driver architecture can affect whether an application can use DBMS-specific SQL.
When the driver accesses the physical data directly, the driver acts as both driver and data source. The driver must process both ODBC calls and SQL statements. Developers of file-based drivers must write their own database engines.
When a separate database engine is used to access physical data, the driver processes only ODBC calls. It passes SQL statements to the database engine for processing.
File and DBMS ODBC configurations can exist on a single network.
When a driver is required to work with a variety of data sources, it can be used as middleware. Heterogeneous join engine architecture can make the driver appear as a driver manager. Drivers can also be installed on servers, where they can be shared by a series of clients.
For more information about driver architecture, see Driver Manager and Driver Architecture in the section on ODBC Architecture.
More information about driver issues can be found in the locations described in the following table.
| Issue | Topic | Location |
|---|---|---|
| Compatibility issues with applications and drivers | Application/Driver Compatibility | Programming Considerations, in the ODBC Programmer's Reference |
| Writing ODBC drivers | Writing ODBC 3.x Drivers | Programming Considerations, in the ODBC Programmer's Reference |
| Driver guidelines for backward compatibility | Driver Guidelines for Backward Compatibility | Appendix G: Driver Guidelines for Backward Compatibility, in the ODBC Programmer's Reference |
| Connecting to a driver | Choosing a Data Source or Driver | Connecting to a Data Source or Driver, in the ODBC Programmer's Reference |
| Identifying drivers | Viewing Drivers | Viewing Drivers, in the Microsoft ODBC Data Source Administrator online Help |
| Enabling connection pooling | ODBC Connection Pooling | Connecting to a Data Source or Driver, in the ODBC Programmer's Reference |
| Unicode/ANSI driver and connection issues | Unicode Drivers | Programming Considerations, in the ODBC Programmer's Reference |