databases

1

Introduction to DatabasesIntroduction to Databases

22

DatabasesDatabases

A database is a collection of related pieces of information

A database can be computerised or non-computerised (manual - such as filing system, phone book etc.)

33

Advantages of Advantages of Computerised DatabasesComputerised Databases

speed of information retrieval

storage capabilities easy to update and

delete ease of access multiple access security

44

Disadvantages of Disadvantages of Computerised DatabasesComputerised Databases

privacy and ethical issues security risks training of staff initial expense (equipment, software) software upgrades

55

TerminologyTerminology

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. Firstname, surname, street, suburb

66


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





77










each COLUMN represents a field.

.

88


Every record in the same table has the same fields.

Databases are designed so that each data item is stored only once

99


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.

1010


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.

1111


Other database operations include:

SEARCHING locate the first record to

contain some specific criteria SORTING

sorting the database by a nominated field

1212


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.

1313

Step 1Step 1Determine what data should be stored in each Determine what data should be stored in each

record.record.

• Generate a list and eliminate information Generate a list and eliminate information that is not directly related to the overall that is not directly related to the overall purpose of the database.purpose of the database.

Planning a Database Planning a Database

Careful planning of a database before it is created will prove to be a useful exercise.

1414


Step 2Step 2What operations are to be performed on What operations are to be performed on

the database?the database?• Do these operations require any Do these operations require any

missing information from the list?missing information from the list?• Will there be any need to reduce the Will there be any need to reduce the

list further?list further?

Adjust the list from step 1Adjust the list from step 1

1515


Step 3Step 3• Create a list of fields and field names Create a list of fields and field names

from step 2from step 2• Create a description of the data and Create a description of the data and

their types (text, number, YES/NO their types (text, number, YES/NO etc)etc)

• Design a simple form for a single Design a simple form for a single record on paperrecord on paper

1616


Step 4Step 4

• Create a new database/table using Create a new database/table using your software with the planned your software with the planned fields.fields.

• Enter the data into databaseEnter the data into database

databases

Technology