12 IPT - IS & DBs Flashcards
What are the characteristics of an information system?
1) The organisation of data into information
2) The analysing of information to give knowledge
What are the purposes of an information system?
1) Process transactions
2) Provide users with information about an organisation
3) Help decision making
4) Manage information used within an organisation
Give three examples of IS provided in the syllabus
1) School database holding information on teachers, subjects, classrooms and students
2) Roads and Traffic Authority holding information on vehicles and hodlers of drivers’ licenses
3) Video stores (do they even exist anymore?!) holding information on borrowers and ivodes
Organisation
What are the computer based methods of organising data?
1) Flat file systems
2) Database management systems (to allow the organisation of relational databases) - e.g. Filemaker Pro or Microsoft Acccess
3) Hypermedia:
an extension to hypertext providing multimedia facilities, such as those handling sound and video. (e.g. prezi.com)
Organisation
Compare and contrast computerised vs non-computerised databases
Factors to consider:
- Amount of data held (physical storage vs computer storage)
- Portability (able to send / transfer easily to other people)
- Analysis (can use many parameters to search, e.g. Female, and aged under 30), can be sorted easily
- Security, use of passwords, not able to e copied, easily track people who accesses the database and backup
Organisation
Flat file databases are made up of what elements?
Characters
A group of characters make a field
A group of fields make a record
A group of records make a file
Organisation
Relational databases are made up of what elements?
Entities - made up of a group of attributes
E.g. a car is an entity, a car’s attribute could be its colour, make, model (and other features)
In implementation, entities become tables - attributes become fields
Entities are connected to each other through relationships:
- 1:1
- 1: M
- M:M (which cannot be implemented but needs to be normalised)
Organisation
What is the purpose of a data dictionary and what does it consist of?
Purpose:
Collection of descriptions of the data objects or items in a data model for the benefit of programmers and others who need to refer to them
It is a table that consists of columns labelled:
- Field name
- Data type
- Data format
- Field size
- Description
- Example
Organisation
Given a scenario, what are the steps to create a schema (schematic diagram or ERD - Entity Relationship Diagram)?
1) Identify the nouns
2) Identify the verbs
3) Connect them to make a sentence - ensure there is no M:M relationships.
- –> M:M relationships are broken down to 1:M and M:1
Organisation
What does it mean to ‘normalise’ the data?
Normalisation is the process of organizing the columns (attributes) and tables (relations) of a relational database to minimize data redundancy.
1NF (First Normal Form): Your typical flat file DB
2NF (Second Normal Form): has data such as “name” rather than “first name” and “second name”, or “address”, rather than “street no”, “street name”, “suburb”, etc.
We usually normalise it to 3NF (third normal form), ie. there is no “student name”, it is “student first name”, “student second name”
Organisation
What elements are hypermedia made of?
(think prezi)
Nodes and links (a link is created between two nodes)
Uniform resource locators (URL)
meta data such as HTML tags
Organisation
What are the tools to organise hypermedia?
1) Storyboard to represent data organised using hyperlinks
2) Software that allows text, graphics and sounds to be hyperlinked
Storage and Retrieval
Why use a DBMS?
DBMS such as Filemaker Pro or Microsoft Access allows data to be stored, retrieved and analysed.
They usually come with search functions via their user interface, and data is easily linked from one table to another.
Storage and Retrieval
Differentiate between online and offline database storage.
Offline databases - cannot be accessed on a network, i.e. not just the Internet but also Intranet. This makes the database more secure, however it can be less accurate as data cannot be updated in realtime.
Online databases - can be accessed through a network, including Intranet and Internet
Storage and Retrieval
Encryption and decryption
Symmetric & Asymmetric
