Databases

Searching and Sorting

SIMPLE searchA SIMPLE search is when you use only ONE field to search the database.

e.g. Searching a football database to find all teams that play in Spain

So you would use COUNTRY = “Spain” (only ONE field is used)

Team Country Stadium Colours Star Player

Liverpool England Anfield Red Gerrard

Real Madrid Spain Bernabau White Van Nistelrooy

AC Milan Italy San Siro Red/ Black Kaka

Barcelona Spain Nou Camp Red/ Blue Ronaldinho

Bayern Muncih Germany Allianz Red Riberry

COMPLEX searchA complex search uses TWO OR MORE fields to find information

So searching the same database would be as follows

COUNTRY = “Spain” AND Colours = “White”

Team Country Stadium Colours Star Player

Liverpool England Anfield Red Gerrard

Real Madrid Spain Bernabau White Van Nistelrooy

AC Milan Italy San Siro Red/ Black Kaka

Barcelona Spain Nou Camp Red/ Blue Ronaldinho

Bayern Muncih Germany Allianz Red Riberry

Examples of Simple searches

• Eye Colour = “Blue”

• Country = “Italy”

• Language = “Spanish”

• Stays in = “Lochwinnoch”

Anything that uses just ONE field in a database is a SIMPLE search

More SIMPLE searchesIf you have a numeric field then it is possible to search that in a slightly different way.

Look at the extract from countries database

Country Capital City Currency Population (millions)

Language

Egypt Cairo pound 80.3 Arabic

Israel Jerusalem Shekel 6.4 Hebrew

Latvia Riga Lats 2.3 Latvian

Japan Tokyo Yen 127.3 Japanese

Brazil Brasilia Real 190 Portuguese

Portugal Lisbon Euro 10.6 Portuguese

Since it is a numeric field we can treat the contents as a number therefore

Population > 100 gives 2 countries Japan and Brazil

More COMPLEX searches

• Eye colour = “Blue” AND Hair Colour = “Brown”• Town = “Johnstone” AND Primary = “Thorn”• Currency = “Euro” AND Population > 20 million• Cost < £1 AND Type = “drink”• Height > 2m AND Right handed = “Yes”• Resort = “Corfu” AND Cost < £400

SORTING a database

• Sorting a database involves using ONE or MORE fields and putting them in order. You can either sort

• ALPHABETICALLY (a-z or z-a)• NUMERICAL (ascending or descending)

YOU HAVE TO TELL THE DATABASE WHAT FIELD YOU ARE SORTING THOUGH

More SORTINGName Height

(m)

Eye Colour

Right Handed

Jane 1.6 Blue No

Bill 1.7 Hazel Yes

Bob 2.4 Hazel No

Alice 1.8 Green Yes

Name Height

(m)

Eye Colour

Right Handed

Jane 1.6 Blue No

Bill 1.7 Hazel Yes

Bob 2.4 Hazel No

Alice 1.8 Green Yes

Sorted using height field ascending

SUMMARYDo you know the difference between

SIMPLE SEARCH And COMPLEX SEARCH

Make sure you tell the database which FIELD or FIELDS you intend to search.

Do you know the difference between

Sort ascending or descending

Numerical Sort and Alphabetical Sort