Introducing SQL and Relational Databases

The Front End of the Chain

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This video segment explains the components of a database system and how they are related.


  • application programs
  • application developers

About this video

Allen Taylor
First online
12 January 2019
Online ISBN
Copyright information
© Allen Taylor 2019

Video Transcript

Speaker: A data processing system that performs some job is made up of a chain of components and information flows back and forth along the chain. In this lesson, we’ll discuss the component parts of that chain. Those parts are the user, the database application, the database management system also known as the DBMS, and the database. We’ll also discuss the flow of information back and forth along the chain.

The first link in the chain is the user, the person who asks questions of the system and receives answers to those questions. There are several layers of hardware and software between the user at one end of the chain and the database at the other end. Each layer performs an important job in requesting the information that the user wants and then conveying it back to the user. The user interacts with the system using a keyboard and mouse as input devices and a graphical user interface of some kind as an output device. The user interface, the second link in the chain, communicates with the third link, an application program. Application programs are written to perform a specific task or a set of tasks using the data in a database. That data could potentially be used in many ways. However, if you want to perform one specific job that uses that data, you need an application program that’s written specifically to perform that job. Thus it’s possible and indeed common to have different application programs said all operate on the same data, in the same database, to meet different objectives. For example, and inventory application program and a sales application program might both access the same product data. Writing application programs is the main job of database application developers. These are the people who will use SQL to the fullest extent and who must have the deepest understanding of it.