Set B - (pg 126)

1. C
2. C
3. A
4. B
5. C
6. D
7. D
8. B
9. A
10. B

Adv/Disadv : Flat file database system

duplicate of data -redundancy
copy or data -> have to write it out
takes up too much soon
can not be updated easily

adv: no need for power

T1 Week2: Methods of organsising databases: Flatfile DB (pg 119)

1. Read pg 119 - identify three computer based methods of organiising data

• Flatfile
• Realtional
• Hypertext/hypermedia/hyperlinks

2. Read page 121 - 122 on choosing appropriate field data types. summarise what must be considered when selecting data types.
Arithmetic operations: numeric data type,
Digits: no mathematical operations:-> text data type
Dates and Times: - dates and times
Data Text: limited number of characters, cannot be indexed
Unlimited characters : Memo
Numeric data: determine if its an interger or not. -> calculates the number of possible variations, roughly each character on the key board is a bite.
Numbers: Currency or money values -> use currency data type

• Fixed point: specifies how many decimal points - rarely used, doesnt represent accurately e.g has more that 2 decimal points, reserved for specialised docs, limited representation
• Floating: use of any number of decimal, commonly used, more range, more versatile, 7 significant figures.

Sorting a text field:  ascending sort of text -> 0,1,2,3 ... A,B,C
Alpha numeric characters: e.g.
1
10
103
12
2
21

value of currency: modified forms of fixed point representation

3.  Create a data dictionary (http://bettscomputers.com/moodle/course/view.php?id=26&topic=all#datadictionaries ) for the information system you documented last week (RTA, Video Store or School). Use sample HSC question on pg 123 as a guide. 

T1 Week 1: "Group Tasks" - pg 112 & pg 113

Software description to match DFD of School Timetable:

SQL server DBMS: Create Initial Timetable
LAN: Genertate student, teacher, adn locate teacher and student timetables and execute timetable query.
Timechart: Create initial timetable, generate teacher and student timetable.
SAS timetable module: Locate teacher or student, execute timetable query.

Classify external entities on C.D (fig 2.4) as either source and/or a sink.

Vocal Inspectors: Source,
Customers: Source, sink
Police departments: Source, sink
Other governemnt departments: Source, sink
Vehicle Dealers: Source
Insurance Companies:  Source

Context System - School Timetable

csv: comma seperated values: - used for the digital storage of data structured in a table of lists form, importing and exchanging data.

Servers: provide resources and information to a network,
e.g email, file storage, internet, databse, library, print servers,

Client:

Node (network PC): has client applications not server application

Information Systems and Databases

The aim of all information systems is to produce information from data for use by the system's end users. End users analyse the information to gain knowledge and only then the system's purpose is achieved.
All information processes are required to produce information for the database, two in particular are:

• data needs to be appropriately organised
• must be able to be stored and retrieved efficiently.

Databases contain the raw data used by majority of information systems.

Examples of Databases Information Systems:

• Flat-File Databases - including non- computer examples 
• Relational Databases
• Hypermedia or hypertext

consists of:

• Environment/boundaries
• Purpose
• Data/information
• Participants
• Information technology
• Information process

Database System

• Fields:(also known as attributes) columns - surname, first name, number, address (seperated into street, sub, postcode etc) 
• Record: (tuple)  rows
• Singe table: - flat file database - alot of redundant data (repeated)
• Relational Database: multiple table, minimises redundancy -> linking tables together with different fields/ data (tables are linked through common fields) uses Primary key: a unique identifier, I.D field - >table
• Data Types: texts (alpha numeric - number, symbols and letters), numeric, boolean - yes/no or true/false or 0,1, memo - unlimited length, date/time, objects (digital - pictures/images/audio files, docs), html\
• Database Management System: e.g. access, file maker