Transcript Introduction to Databases

Databases
A database is a collection
of related pieces of
information
 A database can be
computerised or noncomputerised (manual such as filing system,
phone book etc.)

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Advantages of
Computerised Databases
speed of information
retrieval
 storage capabilities
 easy to update and
delete
 ease of access
 multiple access
 security

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Disadvantages of
Computerised Databases
privacy and ethical issues
 security risks
 training of staff
 initial expense (equipment, software)
 software upgrades
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Terminology
A database or a table within a
database is made of RECORDS
 RECORDS contain information about
a single item in the database/table.
 Each record contains FIELDS.
 A FIELD is a category of data that
has been broken down into its
simplest form.

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Firstname, surname, street, suburb
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Terminology

In a database or table each ROW
represents a record
ID
CDTitle
Units In Stock
Unit Price
1
Joe Cocker Essentials
3
$28.00
2
The Beatles
4
$35.00
3
Aussie Country Hits
2
$19.95
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Terminology

.
each COLUMN represents a field.
ID
CDTitle
Units In Stock
Unit Price
1
Joe Cocker Essentials
3
$28.00
2
The Beatles
4
$35.00
3
Aussie Country Hits
2
$19.95
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Terminology
Every record in the same table has
the same fields.
 Databases are designed so that each
data item is stored only once
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Terminology
The method of retrieving information
from the database is known as
QUERYING the database.
 A query allows you to display a set of
records which meet certain criteria



students in year 9
people with postcode 6192 etc.
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Terminology
Information taken from a database
and designed for hardcopy (printout)
is referred to as a REPORT.
 Reports can be generated from
tables or queries.
 Reports can be formatted in many
different styles depending on the
target audience.

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Terminology
Other database operations
include:
 SEARCHING


locate the first record to
contain some specific
criteria
SORTING

sorting the database by a
nominated field
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Terminology
Some database applications also
provide a user friendly interface
called a FORM.
 Forms are used to display data from
a table or query in an easy to read
format.
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Planning a Database

Careful planning of a database
before it is created will prove to be a
useful exercise.
Step 1
Determine what data should be stored in each
record.
• Generate a list and eliminate information
that is not directly related to the overall
purpose of the database.
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Planning a Database
Step 2
What operations are to be performed on
the database?
• Do these operations require any
missing information from the list?
• Will there be any need to reduce the
list further?
Adjust the list from step 1
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Planning a Database
Step 3
• Create a list of fields and field names
from step 2
• Create a description of the data and
their types (text, number, YES/NO
etc)
• Design a simple form for a single
record on paper
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Planning a Database
Step 4
• Create a new database/table using
your software with the planned
fields.
• Enter the data into database
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