Overview

IT Applications - II — building a real database application

In your first-year Information Technology course you learned how a computer system is built, how it is programmed, and how data is organised in a database. This second-year applications chapter puts all of that together for a single, very practical goal: building a working database application — the kind of software a shop, a school office or an online store actually runs on. You will see that almost every useful business program is really two parts joined together — a front-end that a person sees and works with, and a back-end that quietly stores the data — and that the skill of an application developer lies in designing both halves well and connecting them correctly.

The chapter is organised in the order you would actually build such a system. It opens with the concept of e-business — using computers, software and the internet to run commercial activity — because that is the setting in which most database applications you will meet as a commerce student are used, from online stores to billing and inventory systems. It then introduces the two-part (front-end and back-end) structure that every database application shares, and takes each part in turn: the front-end interface (the screens, forms and controls the user works with), the back-end database (the tables where the data is safely stored), and the all-important connectivity that lets the front-end read from and write to the back-end. The chapter closes by developing a database application end to end — walking through the design, the interface, the tables and the connecting code that turn the separate pieces into one working system.

None of the ideas here belongs to any one product or textbook. The separation of an application into a presentation layer and a data layer, the use of the Structured Query Language (SQL) to talk to a relational database, and the standard steps of opening a connection, sending a query and handling the result are the well-established, general principles of how database applications are built anywhere. What is specific to the Odisha CHSE Information Technology syllabus is the selection of these topics and the Std-12 depth at which you must be able to explain and apply each — which is exactly what the sections below develop, in order. Wherever a short piece of code helps, it is shown in a neutral, general form (plain SQL statements and simple pseudo-code) so that you learn the idea rather than the exact wording of any one tool.