There are basically two types of ODBC architecture:
Single Tier ODBC drivers
Multiple Tier ODBC drivers
Single tier drivers, such as the MicrosoftÂ® AccessÂ® driver, often operate directly on a database file or files.
A single tier ODBC driver processes both ODBC calls and the actual SQL commands.
In most cases, a configuration using a single tier driver can be contained on just one computer.
Multiple tier drivers are more common, and are typically used with a remote database server such as OracleÂ® and SQL Server.
Multiple tier ODBC drivers process ODBC calls made by the application, but pass the actual SQL command to the database system.
ODBC architecture of Microsoft Access is simpler than the typical server architecture. The following figure illustrates the ODBC architecture of Access and other single tier ODBC drivers.
There is no database server computer, client support layer, or network in the figure. The Access ODBC driver works directly on the database file. In this simplest configuration, the database file is located on the same computer as the application.
By using Microsoft networking, Novell networks, and the like, the database file could be located on another computer just like any other shared file. In this way, an Access database could be shared among several computers and applications.
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ODBC - ODBC Architecture (Single Tier)