Ken Lassesen
Microsoft Developer Network Technology Group
August 2, 1995
Click here for a diagram of the Remote Data Object in various graphics formats.
This article consists primarily of a graphic map of the Remote Data Object (RDO), showing its properties, methods, and child objects. The map provides a quick reference to this object. This object is licensed for use only with Visual Basic® 4.0 Enterprise Edition.
The Remote Data Object (RDO) uses Remote Procedure Calls (RPC) to communicate with database servers via the Open Database Connectivity (ODBC) driver manager and a specified server driver. This approach insulates the developer from many database-programming complexities while providing high-level data access objects, properties, and methods. This object is licensed for use only with Visual Basic® 4.0 Enterprise Edition.
A map is a good learning aid and a quick reference when developing an application. After producing a map, I found that it was easy to work with the object: I just post the appropriate map on my wall for quick reference, which is a lot faster than clicking objects in a Help file one by one to discover their properties and methods.
Because Figure 1 is unreadable online, I have included the two most common graphics formats—encapsulated PostScript™ (.EPS) and Windows® metafile (.WMF)—as well as a copy of my original Shapeware® Visio™ version 3.0 file (.VSD). The first two formats can be printed across multiple pages using any of the commercial graphics applications—such as Adobe™ PageMaker™, Corel® Draw, or Microsoft® Publisher—or using Microsoft Excel. The original Visio file is included for those who have a copy of Visio and wish to modify the diagram easily.
Figure 1. The Remote Data Object map
The objects and collections in Figure 1 are defined in Table 1.
Table 1. Object and Collection Definitions
| Object or Collection | Definition |
| rdoEngine object | This object represents the remote data source. As the top-level object, it contains all other objects in the hierarchy of remote data objects. |
| rdoErrors collection | This collection contains all stored rdoError objects. Each rdoError object applies to a single operation involving remote data objects. |
| rdoError object | This object contains details about remote data access errors. |
| rdoEnvironments collection | This collection contains all active rdoEnvironment objects of the rdoEngine object. |
| rdoEnvironment object | This object contains a logical set of connections for a particular user ID. It contains open databases, provides mechanisms for simultaneous transactions, and provides a security context for data manipulation language (DML) operations on the database. |
| rdoConnections collection | This collection contains all open rdoConnection objects opened or created in an rdoEnvironment object of the remote database engine. |
| rdoConnection object | This object represents an open connection to a remote data source and a specific database on that data source. |
| rdoPreparedStatements collection | This collection contains all rdoPreparedStatement objects in an rdoConnection. |
| rdoPreparedStatement object | This object is a stored definition of a query. An rdoPreparedStatement object corresponds to a prepared query definition. Think of this object as a compiled SQL statement. |
| rdoColumns collection | This collection contains all stored rdoColumn objects of an rdoResultset, rdoPreparedStatement, or rdoTable object. |
| rdoColumn object | This object represents a column of data with a common data type and a common set of properties. |
| rdoParameters collection | This collection contains all the rdoParameter objects of an rdoPreparedStatement object. |
| rdoParameter object | This object is a parameter associated with an rdoPreparedStatement object. |
| rdoResultsets collection | This collection contains all open rdoResultset objects in an rdoConnection. |
| rdoResultset object | This object is the set of rows that results from running a query. |
| rdoTables collection | This collection contains all stored rdoTable objects in a database. |
| rdoTable object | This object is the stored definition of a base table or an SQL view. |