Access 2003 VBA Programmer's Reference

Chapter 7. Using ADO to Access Data

In the last chapter, you were introduced to one of the two data access models that Access supports: Data Access Objects (DAO). In this chapter, we will closely examine the other model: ActiveX Data Objects (ADO).

Recall from Chapter 6 that DAO was the default data access technology in the early versions of Access. In fact, Access was bound so closely to the Jet database engine by the fact that developers used Access as both the front-end user interface and the back-end data store that they rarely felt a need for anything else. As applications design evolved from standalone to client/server architectures, the need to connect to and access data from disparate data sources became more and more important. Although Microsoft made several attempts at evolving DAO into a remote data access technology, its real forté was in accessing data from local Jet databases. This is where ADO comes in. When you need to connect to external data sources, you need to start using ADO, because ADO is specifically designed to connect to a wide variety of external data sources.

ADO is a part of Microsoft's data access vision of the future, called Universal Data Access (UDA), in which a single method is used to retrieve data from any data source, which may include relational databases, the mainframe indexed sequential access method/virtual storage access method (ISAM/VSAM), hierarchical databases, e-mail, disk files, graphical data, and so on.

OLE DB (Object Linking and ...