The following table shows two underlying technologies that support data-source or data-bound controls.
ADO is a COM wrapper of OLE DB that facilitates writing data access applications (consumers). OLE DB is a COM-based universal data access technology, allowing you to use any data source, not just indexed, sequential access methods (ISAM) and SQL-based databases.
OLE DB providers can access data from a variety of data sources and is not limited to SQL queries to retrieve data but rather can use queries as defined in the provider.
RDO is the COM wrapper of ODBC. ODBC, a C-based API, allows general-purpose (heterogeneous) data access. However, RDO relies on SQL as the command language to access data.
You might consider using the ADO-based data-access controls rather than the RDO data-access controls.
The following table shows the main differences between ADO and RDO data controls.
- Data-bound controls
RDO data-bound controls use the ICursor interfaces; ADO controls use the OLE DB IRowset interface. In both cases, the interfaces used by the controls return a rowset.
The RDO-based data-bound controls were designed to work best with Visual Basic. As such, some functionality of RDO data-bound controls, most notably in formatting, is not available in Visual C++ applications. This problem is not present in the ADO databinding controls.
- Data controls
ADO data controls implement the IDataSource interface and RDO data controls implement the IVBDSC interface. You can call an IDataSource method to receive an IRowset interface pointer. Similarly, you can call an IVBDSC method to get an ICursor interface pointer.