IS201: Database Theory - Database systems

Data

Facts and statistics collected for reference or analysis

Information

The result of processing raw data to reveal its meaning

Knowledge

Implication of familiarity and understanding of information

Wisdom

When knowledge is guided by judgement, ethics and experience

Data management

A discipline that focuses on proper generation, storage and retrieval of data

Database

A shared, integrated computer structure that stores a collection of end-user data and metadata

End-user data

Raw facts of interest to the end users

Metadata

Describes the data characteristics and the set of relationships that link the data found within the database

Database management system (DBMS)

A collection of programs that manages the database structure and controls access to the data stored in the database

Advantages of DBMS

• Improved data sharing and security

• Better data integration

• Minimised data inconsistency

• Improved data access and decision making

• increased end-user productivity

Types of databases

• Single-user database

• Multiuser database

• location classified database

• data type classified database

Example of single-user database

desktop database which is a single-user database on a personal computer

Examples of multiuser databases

• Workgroup database: supports a small number of users or a specific department

• Enterprise database: supports many users across many departments

Examples of location classified databases

• Centralised database: supports data located at a single site

• Distributed database: Supports data distributed across different sites

• Cloud database: created and maintained using cloud data services

Examples of data type classified databases

• operational database: designed to support a company’s day-to-day operations

• Analytical database: stores historical data and business metrics for decision making via business intelligence

Business intelligence

A comprehensive approach to capture and process business data, generating information that supports decision-making

2 main components of analytical databases

• Data the warehouse stores in a format optimised for decision support

• Online analytical processing (OLAP)

OLAP: component of analytical databases

A set of tools for retrieving, processing and modelling data from a data warehouse to support business analytics and decision-making

Types of database structures

• Unstructured data

• Structured data

• Semi-structured data

Unstructured data

Data that does not fit a predefined data modelS

Structured data

The result of formatting data to facilitate storage and use in a predefined data model

Semi-structured data

Data that has already been processed to some extent but not all the data is guaranteed to meet the structure

NoSQL

Non traditional DBMS designed to handle an unprecedented volume, variety, structure and velocity of data

Database design

The activities that focus on the design of the database structure used to store and manage user-end data

Effects of a well-designed database

These databases facilitates data management and generates accurate and valuable info

Effects of a poorly designed database

These databases cause difficult-to-trace errors that may lead to poor decision-making

Evolution of file systems

1. Manual file systems

2. Computerised file systems

3. Modern end-user productivity tools

Weaknesses of using file systems for data processing

• Lengthy development times

• Difficulty getting quick answers

• Complex system admin

• Lack of security and limited data sharing

• Extensive programming required

• Structural and data dependencies

Components of DBMS

• Hardware

• Software

• People

• Procedures

• Data

Functions of DBMS

• Data dictionary management

• Data storage management

• Data transformation and presentation

• Security management

• Multiuser access control

• Backup and recovery management

• Data integrity management

• Database access languages

• Database communication interfaces

Data dictionary

A detailed description of all tables in a database created by the user and desgner

System catalogue

A detailed system data dictionary that describes all object within the databaseD

Disadvantages of DBMS

• Increased costs

• Management complexity

• Maintaining currency

• Vendor dependence

• Frequent upgrade/replacement cycles