Although you can access any ODBC data source with RDO and the RemoteData control, RDO is designed to take advantage of intelligent database servers, like Microsoft SQL Server and Oracle, that use sophisticated query engines. If you connect to ODBC drivers that are not fully ODBC Level II compliant or to a less sophisticated data source, many RDO features cannot be enabled.
RDO 2.0 has relaxed many of the ODBC compliance requirements imposed by RDO 1.0. Specifically, RDO 2.0 now requires that your ODBC driver support only one Level II compliant operation that enables the SQLNumParams ODBC API function. Without support for this ODBC Level II function, RDO cannot create the rdoParameters collection and parse parameter markers in SQL statements. However, if the driver does not support the SQLProcedureColumns and SQLDescribeParam functions, then your code must supply the direction and data type for each parameter in the rdoParameters collection.
While some drivers can be used to create and execute queries, if your driver does not support creation of the rdoParameters collection, RDO fails quietly and simply does not create the collection. As a result, any reference to the collection results in a trappable error.
If you use RDO to access Microsoft Jet engine databases, the Jet engine must be loaded into memory and all ODBC requests are routed through Jet operations. Not only can this require more RAM and CPU resources than using DAO, but many RDO functions are not supported by the fairly limited Jet ODBC drivers.
RDO is implemented as a 32-bit ActiveX interface, so your target system must be running Windows 95 or Windows NT.
In addition, RDO is only licensed to Visual Basic Enterprise Edition developers. While an RDO program can be compiled and distributed along with the RDO components to an unlimited number of machines, the distributed version is only licensed for run-time operation. Other Microsoft Office platforms do not have a run-time mode or a license to act as an RDO development platform. However, ODBCDirect is a licensed interface to RDO that can be used on Microsoft Office platforms.
Note RDO and the RemoteData control are 32-bit features of the Visual Basic, Enterprise Edition. You cannot develop code or use the RDO object library or RemoteData control in the Professional or Learning Editions of Visual Basic or on 16-bit platforms.