Download - Databases
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Introduction to DatabasesIntroduction to Databases
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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.)
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Advantages of Advantages of Computerised DatabasesComputerised Databases
speed of information retrieval
storage capabilities easy to update and
delete ease of access multiple access security
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Disadvantages of Disadvantages of Computerised DatabasesComputerised Databases
privacy and ethical issues security risks training of staff initial expense (equipment, software) software upgrades
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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
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TerminologyTerminology
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
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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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
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
TerminologyTerminology
each COLUMN represents a field.
.
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TerminologyTerminology
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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TerminologyTerminology
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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TerminologyTerminology
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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TerminologyTerminology
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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TerminologyTerminology
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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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.
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Planning a Database Planning a Database
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
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Planning a Database Planning a Database
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
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Planning a Database Planning a Database
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