DATABASE MANAGEMENT SYSTEMS

Introduction

         Data is a collection of raw facts and figures which, when processed translates into facts or information. The nature of data demands storage and retrieval when needed. Thus, storing data becomes necessary based on that reasoning. Data can be stored in files or databases. However, what is a database? How different is it from a file based system? This article approaches databases from an academic point of view.

Old is Gold (File-based System)

         “The best way to know where you are and going”, says an old proverbial, “is to know where you have come from”. Data storage started with flat file system. It was the first attempt to computerize the manual paper files and cabinet system. Connolly and Begg (2008), elaborate about file based system as a system where each program defines and manages its own data. Flat files were independent and incompatible, each having its own file extension, attributes and behaviour. Apparently, this succumbed to following limitation.

1.Isolation of data makes it difficult to access related data for both user and application

2.It duplicates data wasting space and resource

3.File structure is hardcoded and alterations are difficult to make (program-data dependence).

4.File formats are incompatible

5.No standardised queries for mining the data.

Old is Gone (Database systems)

         The world is thirsty of efficient system; this is where the file based system lost its battle as the best data storage. Database took over, as to when was that, hahaha! Join a history class. That was not funny, but, we are addressing databases not history of databases. Then, what is a database? It is a shared collection of logically related data, and a description of data, designed to meet an organization’s information needs (Connolly and Begg, 2008, pp. 15). Amazingly, databases have two structures: internal and external. The internal definition is separate from the external. This allows us to change the internal definitions without interfering with the user objects, provided the external definitions remain the same- a process called data abstraction. Databases are made of entities (Distinct objects like people), attributes (property that describes and object) and relationship (an association between entities), and managed by database management system.

 Database Management System (DBMS)

DBMS and database

         This is a program that provides interaction between the user or application software and the database. It presents the ability to define, create, maintain and control access to database through:

1.Data Definition Language (DDL)– defines data types, constraints, and structure of database.

2.Data Manipulation Language (DML) – generally inserting, updating and deleting records of database

3.Security – ensure authorises access of data.

4.Integrity – maintaining data consistency

5.Concurrency – Allowing multiple accesses to data (share).

6.Recovery – restoring data in-case of failure

Advantages of DBMS

·   Eliminates data redundancy problem

·   Provides data consistency – any update has to be performed only once and could apply to multiple

·   Offers sharing of data (multiple access support)

·   Improves data integrity –ensuring data entered is valid and meets all set constraints.

·   Improved security – protection of data from unauthorised users

·   Allows DBA to enforce necessary defined standards like naming conventions and access rules

·   Offers economies of scales – many applications can access single database hence saving cost

·   Improved data access and response through use of standard language SQL

·   Improved back-ups and recovery services

Disadvantages

·   DBMS are extremely complex and need expertise to handle

·   They can grow into large volumes (size/bulkiness) consuming a lot of space in a system

·   DBMS software is very expensive to purchase

·   They come with an overhead that is may require additional storage hardware

·   Because of its centralised approach it presents a single point of failure in case of any problem

 References

CONNOLLY, T. M., & BEGG, C. E. (2008). Database solutions: a practical approach to design, implementation and management. Harlow, England, Pearson/Addison Wesley.