The ODBC SDK defines the notion of an ODBC Conformance Level for both the ODBC API and the ODBC SQL grammar. Driver vendors are free to implement only as much advanced functionality as they deem appropriate or possible. When we designed the DB Access Module for ODBC, we were confronted with the task of reconciling a wide range of possible driver capabilities. We chose not to write to the "lowest common denominator" as defined by the lowest level of ODBC conformance. We also resisted simulating certain behavior not directly supported by the driver (for example, nested transactions). Instead, we chose the most natural elements defined in the ODBC API and ODBC SQL grammar to implement as much of the functionality declared in the DB Interface Module as possible.

Functionality may vary considerably between ODBC drivers. Applications should be tested against the ODBC driver or drivers that they expect to use at installation sites.