Data Model SS2 Data Processing Lesson Note

INTRODUCTION 

The main effort during the system development life cycle (SDLC) was to produce a set of programs that automate a business process. Processing was the key driver for information systems, not the data or information. As the technology and complexity of the system grew, methodologies and modelling techniques were invented to improve the quality of the deliverables and to ensure that inexperienced programmers could follow repeatable SDLC processes.

DEFINITION OF DATA MODELLING

Data Modelling is the process of structuring and organizing data. The data structures are then typically implemented in a database management system. In addition to defining and organizing the data, data modelling may also impose constraints or limitations on data placed within the structure.

Managing large quantities of structured and unstructured data is a primary function of information systems. Data Models describe structured data for storage in data management systems such as relational databases. They do not describe unstructured data such as word-processing documents, email messages, pictures, digital audio and video.

CONCEPT OF DATA MODELLING

1. Data modelling techniques and tools help to capture and translate complex system designs into easily understood representations of data flows and processes, creating a blueprint for construction and re-engineering.
2. Data Models provide a structure for data used within the information system by providing a specific definition and format.
3. The Data Model shows the data flow and logical interrelationship among different data elements.
4. Compatibility of data can be achieved if a data model is consistently used across the systems.

The term data model refers to two different things: a description of data structure and the way data is organized using the Database Management System (DBMS).

DATA STRUCTURE

A data model describes the structure of the data within a given domain and, by implication, the underlying structure of that domain itself.

DATA ORGANISATION

A data model also describes how to organize data using a database management system.

THE APPROACH IN DATA MODELLING

There are different approaches to data modelling, including;

1. Conceptual Data Modeling: Conceptual data modeling identifies the highest-level relationships between different entities. This is the first step in organizing the data requirements.
2. Logical Data Modeling: Logical Data modelling illustrates the specific entities, attributes and relationships involved in a business function. It serves as the basis for the creation of the physical data model.
3. Physical Data Modelling: Physical Data Modelling represents an application and database-specific implication of a logical data model and describes the physical means used to store data.