2. • A database is an organised
collection of data.
• Non-computerised databases
include:
• telephone book
• address book
• recipe cards
3. • Advantages of non-computerised
databases:
• no power required
• no training required
• inexpensive
• data not a linked security risk
• Advantages of computerised
databases:
• easily edited
• large storage
• fast retrieval
• display options
4. • A flat file database organises data
into a single table.
• Flat file databases organise the data
into:
• files – a block of data; divided
into records and fields
• record – a collection of facts
about one specific entry
• field – a specific category of
data in a database
• character – smallest unit of
data (e.g. letters, numbers,
symbols)
5. • Keys are fields that are used to sort
and retrieve information.
• Keys include:
• single key – derived from one
field
• composite key – made by joining
two or more keys together
• primary key – a field that has a
set of unique values
• secondary key – a field that does
not contain unique data
6. • A relational database organises data
into a series of linked (related)
tables.
• The organisation of data in a
relational database involves a
schema.
• A schema is the data definition for a
relational database.
• It shows the entities, relationships
and attributes.
7. • An entity is the specific thing about
which the data has been collected.
• E.g. in school – student contact
details, merits/demerits, reports,
attendance.
• Each table is one entity.
• An attribute is a defined property of
an entity.
• Attributes are the same as fields in
flat file databases.
8. • A relationship is the way in which
entities are related to each other.
• Entities are related through primary
keys.
• Entities can be related in one of
three ways:
• one to one
• one to many
• many to many
9. • Data modelling is the process of
identifying entities, their attributes
and the relationships between those
entities through certain attributes.
• Some tools that are used include:
• data dictionaries
• schematic diagrams
• normalisation
• Data dictionaries are
comprehensive descriptions of each
attribute.
10. • Each data dictionary contains
metadata such as:
• field name – should be short,
clear and unambiguous
• data type – kind of data (text,
number, date, time, logical
(Boolean))
• field size – number of characters
allowed in an attribute
• description – specifies the
contents of an attribute
11. • The data dictionary is the basis for
database creation.
• If there are multiple designers it
allows them to see if a particular
attribute already exists in another
entity.
• This can help to eliminate data
redundancy, which is the
undesirable duplication of data
within a database.
[p.52 – Complete learning activity 4,
parts (a) & (b) ]
12. • Schematic diagrams are graphical
tools that help define the database
and describe a schema.
• An entity-relationship diagram (ERD)
is a graphical method of identifying
the entities and their attributes and
showing the relationships between
entities.
[Draw Diagram 2.13, p.48]
13. • Hypermedia is a combination of
media whose locations are linked
electronically.
• The information is stored using a
set of documents that may contain:
• text
• images
• video
• audio
• animations
• executable files
14. • Information is retrieved using
hypertext.
• Hypertext is the system that allows
documents to be cross-linked in
such a way.
• A link, or hyperlink, is usually
indicated by a highlighted item.
• One application of hypermedia is the
World Wide Web.
• Each document is accessed through
its uniform resource locator.
15. • A URL is the address of a file or
resource on the Web.
• It links to an Internet Protocol (IP)
number and is unique.
• The URL consists of three parts:
• protocol (http, https, ftp)
• domain name – address of a
specific computer where the
website is hosted
• file path – links to a specific page
or resource.
16. • URL’s must be exact and complete
or they will not work.
• A storyboard is a series of frames,
each representing a different action
or image.
• It is a tool used by hypermedia.
• They consist of navigation paths,
information and graphics.
• They are popular because they are
easy to read and modify.
17. • Four main storyboard layouts are:
• linear – simple sequential path
• hierarchical – branching top-
down design
• non-linear – no structure
• combination – a blending of the
above
• Web pages are created using
hypertext markup language (HTML).
18. • HTML is a set of special instructions
that describe how the parts of a
document are displayed.
• They are actually text files with
special HTML instructions.
• An HTML editor is a program that
specialises in writing HTML code.
• Instructions are given using HTML
tags.
• These tags are metadata because
they are information about the data.
19. • Links are achieved though text or
images using specialised HTML
tags.
• Tags are usually paired to start and
end an instruction.
• E.g. <B> and </B> will make all text
between them bold.
