Appendix G: Driver Guidelines for Backward Compatibility
This appendix provides information for driver writers working on ODBC 3.x drivers that need to support ODBC 2.x applications. For more information about backward compatibility, see Backward Compatibility and Standards Compliance.
This section contains the following topics.
Block Cursors, Scrollable Cursors, and Backward Compatibility for ODBC 3.x Drivers — New features are features that exist in ODBC 3.x and not in ODBC 2.x. ODBC 3.x drivers generally do not have to worry about backward compatibility with new features because ODBC 2.x applications never use them. The sole exceptions to this are features related to SQLFetch, SQLFetchScroll, SQLSetPos, and SQLExtendedFetch; for more information, see , later in this appendix.
Mapping Deprecated Functions — Duplicated features are features that are implemented differently in ODBC 3.x and ODBC 2.x. ODBC 3.x drivers do not have to worry about backward compatibility with duplicated features because the Driver Manager always maps ODBC 2.x features to ODBC 3.x features when calling an ODBC 3.x driver. Thus, an ODBC 3.x driver sees only ODBC 3.x features. For more information about these mappings, see , later in this appendix.
Behavioral Changes and ODBC 3.x Drivers — Behavior changes are features that are handled differently in ODBC 3.x and ODBC 2.x. ODBC 3.x drivers have to worry about behavior changes and act in response to the SQL_ATTR_ODBC_VERSION environment attribute set by the application.