The implementation of the RWDBCursor class in the DB Access Module for ODBC is subject to many restrictions. In most cases, these restrictions are imposed by the capabilities of the underlying driver.

Some drivers require a unique index on every table involved in every cursor operation; e.g., Microsoft SQL Server. An error from the ODBC driver will result if any table lacks a unique index when required.

Scrolling cursors are implemented by setting the SQL_ATTR_CURSOR_SCROLLABLE statement attribute to SQL_SCROLLABLE. This is done automatically when a cursor of type RWDBCursor::Scrolling is requested.

For cursors, memory is allocated and bound to receive the column data. Therefore, data is fetched only up to the size of the allocated memory. Please refer to the member functions of class RWDBODBCLibEnvironmentHandle to control the size of these memory allocations for large character and binary data.