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Thursday, October 05, 2006

Working with DBISAM Using Microsoft .NET

Working with DBISAM Using Microsoft .NET

In this article Bhuban provides a brief overview about DBISAM and the different ways by which we can interact with the database using Microsoft .NET.

Article Contents:

DBISAM is a word that may seem new for many of us and many would be astonished to know that it is a database.  Like any other database, it has the ability to maintain huge amounts of data.  This article aims at providing an overview of DBISAM and the ways we can interact with the database through .NET.  Let us first discuss about some of the aspects of DBISAM.

DBISAM is an embedded database engine which is available for programming languages that can use ODBC for data access.  DBISAM can be used as a single-user, multi-user or client-server engine.

General Architecture

DBISAM is session based where each session is equivalent to a virtual user.  In a given application there can be many active sessions.  The sessions are of 2 types.

·         Local Session: A local session can directly access the database tables via Windows or Linux APIs to the local storage medium.

·         Remote Session: A remote session uses sockets to communicate to a database server over a network using TCP/IP protocol.

The main drawback of DBISAM is that it does not support Referential Integrity.


DBISAM uses the physical directories in Operating System’s file system to represent databases. The tables in DBISAM are represented by three physical files in the database.

·         .dat (Data Files) which are the actual tables in the Database that store records.

·         .idx (Index Files) which store index definitions and pages.

·         .blb (BLOB Files) that store BLOB blocks related to tables.

Data Types

The data types used in DBISAM are also supported by other databases or relational databases, but with some exceptions.  A comparison between the data types of DBISAM and SQL Server is given below.

Working with DBISAM Using Microsoft .NET


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