DATABASES

DATABASEDefinitionsA database is a structured collection of similar information which you can search through.

File A collection of structured data on a particular topic. A file is

made up of records.

Record Information held about one person or thing. A record is made up of fields.

Field A single item of information.

TYPES OF FIELDS

Text holds letters, numbers and symbols

Numeric hold numbers for calculations

Date holds a date

Time holds a time

Graphic holds a picture

Calculated field performs a calculation on the contents of one or more fields.

SearchingThe search facility allows you to look for information in the

database.

A search may be:

Simple Look for records with a match on one field ( They have one thing in common.)

eg Hair = “Brown”

Complex Look for records with a match on more than one item in one or more fields.Eg Hair = “Brown” AND Eyes = “Blue”

Comparison operators< Less than< = Less than or equal to= Equal to> = Equal to or greater than> Greater than< > Not equal to

Contains

Eg. To find all records for 1st to 3rd year in a school database you could search for:

Year <= 3rd

Year = ‘3rd’ OR Year = ‘4th’ AND Subject = ‘Computing’

Eg To search a school database for all Standard Grade Computing pupils you could search for:

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In a complex search we need to link the searches together using one of the following operators:

AND Both items required in each recordOR One item required in each record

Sorting

Sorting allows you to arrange the records in a database in alphabetic or numeric order. This can be ascending (A to Z or 1 to 9) or descending (Z to A or 9 to 1)

Sorting on More than one field

When two items are the same in one field they can be separated using a second field for sorting.

For example, it is common to sort lists of names first by surname and then by first name

Example: Field 1: Date of birthField 2: Today's dateField 3: Age

Field 3 is a calculated field and contains the formula: Today’s date - Date of birth

Calculated Field(Also called a computed field). A calculated field allows you to carry out a calculation on another field or fields and return the answer in the calculated field. (similar to

formulae in a spreadsheet).

Other examples of calculated fields often used in reports include totals and sub-totals.

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ReportsAny information on your database that you print out is a

report. You would normally do a search and / or a sort, and then select which fields you want to print.

Size of a fieldThis is the total number of characters, including spaces, needed to hold the information in a field.

Eg. A Field containing the data‘Computing Department’

Would have a field size of 20

Examples of databases include:-Telephone directoryPolice National ComputerA personal Christmas card list

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KeywordsThis is the text used to search a file for a particular entry.

Key FieldThis is a field which contains unique information for each record. That is, each record has a different number or text in the key field. Doing a search for an item on a unique field will only give one record.

Example: SQA has a database of all pupils attempting Standard Grade Exam. Each pupil has a unique candidate number because there will be more than one pupil with the same name and date of birth.

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Data Protection

Definitions:

Data User is a person who holds and uses personal data about others or controls the use of it.

Data Subject is a person about whom personal data is stored by a data user.

The Data subjects have the following rights:

• to know if data is held about them on a computer

• to see a copy of this personal data

• to make corrections if necessary

• to ask for compensation if data is inaccurate or access given to an unauthorised person.

Under the Data Protection Act (1984) data users must:• get and process the information fairly and

lawfully• register what reason they hold it for• hold only relevant information • hold only accurate and up to date information• not keep information any longer than needed• give individuals access to information about

themselves and, where necessary, correct or remove wrong information

• take appropriate security measures.

Exceptions to the Act

There are exceptions to people’s right to see data held about them. The public are denied access to data held by the Police or security forces.

Computer Misuse Act – It is criminal offence to gain unauthorised access to a computer system, including Hacking and writing and spreading Viruses.

Copyright Designs and Patents Act – It is illegal to copy Software. This Act protects copyright owners from having their work copied by others without payment.

Freedom of Information (Scotland) Act 2002- This came into force on January 2005 and enables any person to obtain information from Scottish public authorities.

Other important Acts you need to know:

Misuse of ComputersThe Computer Misuse Act is intended to protect all types of information (not just personal) stored on computer

systems.

HackingThis is the act of trying to gain unauthorised entry to files. This is done by using a wide area network and passwords.

VirusesSome people enjoy writing and distributing computer

viruses which destroy data and cause computers to crash or take up processor time in meaningless calculations. Viruses are usually spread by copying files (from unofficial sources).

To prevent viruses spreading:• Don’t share disks.• Don’t copy software.• Use an anti-virus program to check disks

regularly.

A database is the second general purpose package (along with a word processor) required to produce a mail merged document. Having studied both these packages, we are now in a better position to understand how a mail merge works.

Mail merging is the process of combining details from a database with a standard letter in a word processing package, to produce personalised letters - as many letters as there are records in the database.

Mail Merge

Database Word Processed Standard Letter

Name FlossieYear S1Name JosieYear S5Name PhyllisYear S4

Dear Parent,I am pleased to inform you that your child ___________ has won a prize for the best Computing student in __________Head Teacher.

Having created your database and your standard letter, you are ready to combine the two, filling the gaps in the standard letter with information from the database.

Word Processed Standard Letter with database fields inserted ready for mail merge.

The database field names are used to mark where in the standard letter information from the database will be inserted. These are shown in brackets like so << >> to mark them.

Dear Parent,I am pleased to inform you that your child <<Name>> has won a prize for the best Computing student in <<Year>>Head Teacher.

When the mail merge is performed the field names in brackets are replaced with the appropriate fields from the database. This is done for every record in the database.