Access Database Design and Programming, Second Edition

ADO and OLE DB

As we have seen, the DAO model is the programming interface for the Jet database engine. On the other hand, ADO has a more ambitious goal—it is the programming model for a universal data access interface called OLE DB. Simply put, OLE DB is a technology that is intended to be used to connect to any type of data—traditional database data, spreadsheet data, Web based data, text data, email data, and so on.

Technically speaking, OLE DB is a set of COM interfaces. An interface is just a collection of functions, also called services, with a similar purpose. The term COM refers to the Component Object Model , which is Microsoft’s model for communication between software components. Thus, simply put, OLE DB is a set of functions or services.

Figure 17.2 gives an overview of ADO and OLE DB from a VB programmer’s perspective.

Figure 17-2. OLE DB and ADO

Data Stores

The purpose of OLE DB is to provide applications with universal data access—that is, with a common method for accessing data in essentially any format, including traditional database formats, text formats, spreadsheet formats, email formats, file system formats, web-based formats, and more. OLE DB uses the term data store to refer to any data that can be accessed through the OLE DB services. The term data source seems to be a synonym for data store, although this term is used in different ways in other related contexts ...