Chapter 8 -- The ODBC API

Chapter 8

Prior to Open Database Connectivity (ODBC), clients who interacted with data located on a remote server had to use a proprietary API or an embedded SQL code. An example of a proprietary API is the BTRV function used to access data stored in Pervasive Software Btrieve. Calls to BTRV were identical, semantically, regardless of where the data resided, but the code would have to be recompiled for each client platform and relinked as well. Of course, getting data from other sources required other methods .

The more convenient option for accessing server data was embedded SQL codeSQL code was embedded in the source program and a precompiler was required to properly set up the SQL calls. This model was acceptable as long as most programs dealt with only a single data source. If you had to access data sources from multiple database vendors , you needed multiple versions of a program and you needed to know the name of each destination database at compile time.

In the 1980s, the proprietary API and embedded SQL models began to fail under the weight of multiple databases and the widespread availability of applications such as Lotus 1-2-3, Microsoft Excel, and Microsoft Access. Users of these PC programs needed to access information from a variety of server-based data sources, and they wanted convenient access from within their favorite productivity applications. Blending data from both PC and mainframe data sources became a necessity.

ODBC was developed to provide client workstations with the ability to attach to databases located on remote servers. Within server-based development, ODBC has recently become a significant force because of the role of Microsoft Windows NT and Windows 2000 in the network operating systems market and the emergence of Windows 2000 Server as a Web host. The reliance of most Web servers on convenient data connectivity also has placed new emphasis on ODBC. Furthermore, using ODBC is the primary way to access data from the script-based Active Server Pages provided by Microsoft Internet Information Server (included with Windows 2000 Server).