Understanding the RDO Object Model

Remote Data Objects (RDO) is a thin object-model layer over the ODBC application programming interface (API). RDO depends on the ODBC driver and the database engine for much of its functionality. Data access using RDO is intended for only ODBC relational databases.

Note   While it is technically possible to use RDO and ODBC drivers to access Microsoft Jet and ISAM databases, it requires complex coding and is not recommended.

The RDO object model includes a number of objects, properties, and methods specifically designed to work with stored procedures and their arguments, input and output parameters, and return status values.

The following drawing shows the RDO object model.

There are ten objects in the RDO object model, as described in the following list.

• rdoEngine object   The base RDO object. This object is created automatically when you first access RDO in your application.
• rdoError object   Handles all ODBC errors and messages generated by RDO. This object is created automatically.
• rdoEnvironment object   Defines a logical set of connections and transaction scope for a particular user name. This object contains both open and allocated (but unopened) connections, provides mechanisms for simultaneous transactions, and defines a security context for operations on the database. This object is created automatically.
• rdoConnection object   Represents either an open connection to a remote data source, or an allocated, but as yet unopened, connection.
• rdoQuery object   An SQL query statement with zero or more parameters.
• rdoColumn object   Represents a column of data, including data type and common properties.
• rdoParameter object   Represents a parameter associated with an rdoQuery object. Query parameters can be input, output, or both.
• rdoResultset object   A set of rows returned from a query.
• rdoTable object   Represents the stored database definition of a table or view.
• rdoPreparedStatement object   The rdoPreparedStatement object contains a prepared SQL statement and collection of rdoParameter objects. The rdoPreparedStatement object is obsolete (although still supported). You should use the rdoQuery object instead.