Slide 1 Standard Grade Computing Databases. Slide 2 Standard Grade Computing Definitions DatabaseA database is a structured collection of similar information.

Standard Grade ComputingSlide 1

Databases


DefinitionsDatabase A database is a structured collection of

similar information which you can search

through. Eg) Police National Computer

File A collection of structured data on a particular topic. A file is made up of records. Eg) Police criminal file

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

Field A single item of information.Eg) The criminals hair colour, name, eye colour etc


Example

Photo

ID 1Surname Winters

Forename PaulHair BlackEyes Blue

Height (m) 1.8Age 32

Conviction RobberyNick Name Scar Face

Field

Record

File


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


Size of a Field

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

Eg

Forename Surname Date of Birth Sex

Jonathan O'Reilly 08/02/1990 M

Cheryl Thompson 12/09/1989 F

Kevin Delury 23/05/1990 M

Pamela Hamilton 19/12/1989 F

Sarah - Louise Cunningham 31/07/1989 F

Field sizes

15 15 8 1


Field Name Field Size

Forename 15 characters = 15 bytesSurname 15 characters = 15 bytesDate of Birth 8 characters = 8 bytesSex 1 characters = 1 bytes

Size of 1 record = 15 + 15 + 8 + 1 = 39 bytes

For 50 records storage size = 39 X 50= 1950 bytes= 1950 1024= 1.9 kilobytes


Create record

When you create a record you must first consider –

• How many fields should there be.• The data type for each field.• What size each field should be.


Add record

A new record is added to the database.

Eg When a criminal has to be added to the police crime database.

Eg When a new pupil joins a school, their details need to be added to the school database.


Edit record

Is when details in a record need to be updated.

Eg A criminal’s record will need to change when they commit another crime. (Entry in conviction field would change.)

Eg A pupil’s record will need to change if they move house. (Entry in address field would change.)


Create field

Extra information may need to be added to each record in the database.

This means adding a new field.

The new field would be added to all of the records in the database.


Example 1

A new field called colour has been added

Make Model Reg Number

Mercedes SLK M1 ARK

Audi TT S3 ARA

BMW Z4 P21 ETE

Lotus Elise STO 53 THD

Make Model Reg Number Colour

Mercedes SLK M1 ARK Silver

Audi TT S3 ARA Black

BMW Z4 P21 ETE Yellow

Lotus Elise STO 53 THD Red







Sarah - Louise Cunningham 31/07/89 M

Example 2

Name field changed into 2

fields

Name Date of Birth Sex

Jonathan O' Reilly 08/02/90 M






The 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”

Searching


Comparison Operators

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

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

Year <= “3rd”

Eg To find all records for criminals who do not have black hair

Hair <> “Black”


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

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

Year = “3rd” OR Year = “4th” AND Subject = “Computing”


Searching on the Internet – Simple Search

This is when you search the internet for web pages that contain one keyword.

E.g. Hotels


Searching on the Internet – Complex Search

This is when you search the internet for web pages that contain more than one keyword.

E.g. Hotels + Paris


Searching on CD-ROM – Simple Search

This is when you search on a CD-ROM for information that contains one keyword.

E.g. Music


Searching CD-ROM – Complex Search

This is when you search on a CD-ROM for information that contains more than one keyword.

E.g. Rap + music


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)

A sort may be:

Simple A sort on the contents of one field only.Eg Hair in ascending order.

Complex A sort on the contents of two or more fields. Eg Hair in ascending order AND eyes in descending order

Sorting


Alter record format

Databases can be displayed in different ways.

There are 2 different formats for organising your database –

• Card Format• List or Table format


Example of card format

Forename JonathanSurname O'Reilly

Date of Birth 08/02/90Sex M

Forename Thompson

Surname Cheryl

Date of Birth 12/09/89

Sex F

Forename DelurySurname Kevin

Date of Birth 23/05/90Sex M

Forename Sarah - LouiseSurname Cunningham

Date of Birth 31/07/89Sex F


Example of list or table format








Computed Field - Credit

A calculated field allows you to carry out a calculation on another field or fields and return the answer in the calculated field.

It is similar to using formulae in a spreadsheet.

Eg Item Cost Number Sold Total Cost

Coke £0.50 17 £8.50

Chocolate £0.35 23 £8.05

Crisps £0.27 5 £1.35

Irn Bru £0.50 11 £5.50

The computed field Total Cost would contain the formula

Total Cost = Cost * Number Sold


Keywords - Credit

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

Eg) If you were searching the library database and you searched for “potter” you would get books with the word “potter” in their title.

For example Pottery, Harry Potter …


Input and output format - Credit

The user can alter the format of the input screen to make it easier to enter data.

Eg) Enter all of one field before moving onto the next record.

The user can customise the output from a database.

Eg) Creating a report









Slide 1 Standard Grade Computing Databases. Slide 2 Standard Grade Computing Definitions DatabaseA database is a structured collection of similar information.

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