INFS1603 Study Guide - Final Guide: Application Programming Interface, Database Administrator, Database Security
19 Jul 2018
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DATABASE SYSTEMS
DATA VS INFORMATION
Data: meaningful facts concerning things such as people, places, events or concepts
Information: data that has been processed and presented in a form for human
interpretation, often with the purpose of revealing trends or patterns
• Data constitutes the building blocks of information
• Databases help to manage data
• Information is produced by processing data
• Information is used to reveal the meaning of data
• Accurate, relevant and timely information is the key to good decision making
• Good decision making is the key to organisational survival in a global environment
EVOLUTION OF FILE SYSTEMS DATA PROCESSING
• Data: raw facts
• Field: a character or group of characters that has a specific meaning. A field is used
to define and store data
• Record: a logically connected set of one or more fields that describes an entity
• File: a collection of related records
HISTORY OF HANDLING DATA
• Manual filing system
• Computerised filing systems via data files
• Database systems
1) Users communicate their requirements to programmers
2) Programmers build and maintain programs, generating input data
3) Programs communicate directly with files which may be shared by several programs
4) Results eventually filter down to users
PROBLEMS WITH FILE SYSTEMS DATA PROCESSING
• Lengthy development times: even the simplest task required extensive programming
• Difficulty of getting quick answers: the need to write programs to produce even the
simplest reports make ad hoc queries impossible
• Complex system administration: system administration becomes more difficult as the
number of files in the system expands
• Lack of security and limited data sharing: limited in scope and effectiveness
• Structural dependence: access to files were dependent on its structure. Modifications
to these structurally dependent databases are likely to cause bugs; unable to access
data
• Data redundancy: difficult to combine data from multiple sources; data redundancy
exists when the same data is stored unnecessarily at different places
o Poor data security – having multiple copies of data increases the chances for
a copy of the data to be susceptible to unauthorised access
o Data inconsistency – different and conflicting versions of the same data
appear in different places
o Data entry errors – more likely to occur when complex entries are made in
several different files
o Data anomalies – develop when not all of the required changes in the
redundancy data are made successfully (update, insertion, deletion)
• Lack of design and data-modelling skills: results in poor data design leading to a
large degree of redundancy for several data items and other issues
INTRODUCING THE DATABASE
Database: a shared, integrated computer structure that stores a collection of end-user data
and metadata. It is managed through a database management system (DBMS)
• End-user data: raw facts of interest to the end user
• Metadata: data about data, through which the end-user data are integrated and
managed
ROLE AND ADV ANTAGES OF THE DBMS
A DBMS is a data storage and retrieval system which permits data to be stored non-
redundantly while making it appear to the user as if the data is well integrated.
Advantages:
• Improved data sharing: better access to more and better-managed data
• Improved data security: provides framework for better enforcement of data privacy
and security policies
• Better data integration: promotes an integrated view of the organisation’s operations
and a clearer view of the big picture
• Minimised data inconsistency: data inconsistency is reduced
• Improved data access: possible to produce quick answers to ad hoc queries (a spur-
of-the-moment question)
• Improved decision making: better-managed data and improved data access make
it possible to generate better-quality information to facilitate better decisions
• Increased end-user productivity: better information allows for more tasks to be done
TYPES OF DATABASES
Databases can be classified in a number of ways:
• Number of users supported:
o Single-user database, multiuser database, workgroup database enterprise
database
• Where the data is located:
o Centralised database, decentralised database, cloud database
• The type of data stored:
o General-purpose database, discipline-specific database
• The intended data usage:
o Operational database, analytical database
• The degree to which the data is structured
o Unstructured, semi structured, structured
WHY DATABASE DESIGN IS SO IMPORTANT
Database design: refers to the activities that focus on the design of the database structure
that will be used to store and manage end-user data.
A well-designed database facilitates data management and generates accurate and
valuable information used to make good decisions for the business.
DATABASE SYSTEMS
Unlike file systems with many separate and unrelated files, databases consist of logically
related data stored in a single logical data repository.
THE DATABASE SYSTEM ENVIRONMENT
Database system: refers to an organisation of components that define and regulate the
collection, storage, management and use of data within a database environment.
Composed of five major parts:
1) Hardware: refers to all of the system’s physical devices
2) Software: three types of software are needed to make the database system work:
a. Operating system
b. DBMS
c. Application programs and utility software
3) People: all users of the database system
a. System administrators
b. Database administrators
c. Database designers
d. End users
4) Procedures: the instructions and rules that govern the design and use of the
database system
5) Data: the collection of facts stored in the database
DBMS FUNCTIONS
• Data dictionary management
• Data storage management
• Data transformation and presentation
• Security management
• Multi-user access control
• Backup and recovery management
• Data integrity management
Document Summary
Data: meaningful facts concerning things such as people, places, events or concepts. Information is used to reveal the meaning of data. Evolution of file systems data processing: data: raw facts. Field: a character or group of characters that has a specific meaning. A field is used to define and store data: record: a logically connected set of one or more fields that describes an entity. Lack of security and limited data sharing: limited in scope and effectiveness. Structural dependence: access to files were dependent on its structure. Lack of design and data-modelling skills: results in poor data design leading to a large degree of redundancy for several data items and other issues. Database: a shared, integrated computer structure that stores a collection of end-user data and metadata. It is managed through a database management system (dbms) End-user data: raw facts of interest to the end user: metadata: data about data, through which the end-user data are integrated and managed.
