What is Data Dictionary?

1.8.3.5 Data Dictionary

Data dictionary is a catalogue for a system to record details of all data used in the system. Data dictionary provides reference for all data elements in a system. It is useful in locating errors, contradictions and omissions in a data flow diagram and other analysis tools. It contains two types of descriptions for data flowing through the system i.e. data elements and data structure.

·         Data element is the most fundamental level of data. It cannot be further divided. For example, on Order Processing system has INVOICE_NO, INVOICE_DATE and AMOUNT data elements. They do not contain any other elements of data.

·         Data Structure is a set of data elements that are related to one another and collectively describe a system entity such as ORDER, IVOICE and CUSTOMER.

1.8.3.6 Structured English

Structured English is a popular tool for defining process specifications. Its language constructs are English-like and easy to understand. It can easily be related with a popular programming language tool pseudo code.

1.8.4 Analyst Report

Analyst report is generated at the end of system analysis phase. It is submitted to the top management for review.

The report should consist of the following parts:

·         It must explain the current system.

·         It should explain the problems in the current system.

·         It should describe the requirements and recommendations for new system.

1.9 Phase 3: Designing the System

System design phase is used to design the logical model and physical model of the new system. The system design states how the new system will meet the requirement identified in system analysis phase.

1.9.1 Logical Design

Logical design describes the functional capabilities of the new system. It reviews the system requirements and considers the major system components. CASE tools and project management software are used in the phase. MS Project, Gantt chart and PERT chart some commonly used tools for preparing logical design.

1.9.2 Physical Design

Physical design describes how the proposed system will deliver the capabilities specified in the logical design.

It specifies the following:

·         Output requirements

·         Input requirements

·         Storage requirements

·         Processing requirements

·         System control

·         Backup and Recovery procedures

1.9.3 Report

A detailed report is generated at the end of design phase. It is also submitted to the higher management for approval.

1.10 Phase 4: Coding

In this phase, actual system is developed. It consists of writing segments and programs. These segments are combined together at a large stage. This phase requires a lot of time, effort and budget to develop the complete system. Single programmer or a team of programmers develops the system using different tools

1.11 Phase 5: Testing

Complete testing of the system is very important. It is essential to detect errors or problems before using the system. A system can be tested in two stages:

1.     Unit Testing

It is also known as module testing. In this stage, individual units are modules or the systems are tested by using sample data.

2.     System Testing

In this stage all modules are combined to make a complete system. The complete system is then tested as a whole.