An application can retrieve metadata information from the DBMS either by calling ODBC catalog functions or by using INFORMATION_SCHEMA views. The views are defined by the ANSI SQL-92 standard.
If supported by the DBMS and the driver, the INFORMATION_SCHEMA views provide a more powerful and comprehensive means of retrieving metadata than the ODBC catalog functions provide. An application can execute its own custom SELECT statement against one of these views, can join views, or can perform a union on views. While offering greater utility and a wider range of metadata, INFORMATION_SCHEMA views are not often supported by the DBMS. This might change as more DBMSs and drivers achieve compliance with SQL-92.
To determine which views are supported, an application calls SQLGetInfo with the SQL_INFO_SCHEMA_VIEWS option. To retrieve metadata from a supported view, the application executes a SELECT statement that specifies the schema information required.