Interface Conformance Levels
The purpose of leveling is to inform the application what features are available to it from the driver. A leveling scheme based on functions does not sufficiently achieve this goal. In ODBC 3.x, drivers are classified based on the features they possess. Supporting the feature can include supporting the function; it can also include supporting a descriptor field, a statement attribute, a "Y" value for an information type returned by SQLGetInfo, and so on.
To simplify specification of interface conformance, ODBC defines three conformance levels. To meet a particular conformance level, a driver must satisfy all of the requirements of that conformance level. Conformance with a given level implies complete conformance with all lower levels.
Conformance levels do not always divide neatly into support for a specific list of ODBC functions, but specify supported features as listed in the following sections. To provide support for a feature, a driver must support some or all forms of calls to certain ODBC functions (for more information, see Function Conformance), setting certain attributes (see Attribute Conformance), and certain descriptor fields (see Descriptor Field Conformance).
The application discovers a driver's interface conformance level by connecting to a data source and calling SQLGetInfo with the SQL_ODBC_INTERFACE_CONFORMANCE option.
Drivers are free to implement features beyond the level to which they claim complete conformance. Applications discover any such additional capabilities by calling SQLGetFunctions (to determine which ODBC functions are present) and SQLGetInfo (to query various other ODBC capabilities).
There are three ODBC interface conformance levels: Core, Level 1, and Level 2.
These conformance levels have different requirements than the ODBC API conformance levels of the same name in ODBC 2*.x*. In particular, all the features implied by ODBC 2*.x* API conformance Level 1 are now part of the Core interface conformance level. As a result, many ODBC drivers may report Core-level interface conformance.
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