mr c johnston ict teacher g042 – lecture 02 using logical operators to aid searching

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Mr C Johnston ICT Teacher www.computechedu.co.uk G042 – Lecture 02 Using Logical Operators To Aid Searching

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Page 1: Mr C Johnston ICT Teacher  G042 – Lecture 02 Using Logical Operators To Aid Searching

Mr C JohnstonICT Teacher

www.computechedu.co.uk

G042 – Lecture 02

Using Logical Operators To Aid Searching

Page 2: Mr C Johnston ICT Teacher  G042 – Lecture 02 Using Logical Operators To Aid Searching

Session Objectives

Understand how different logical operators can be used to narrow down searches when trying to find information on the internet.

Page 3: Mr C Johnston ICT Teacher  G042 – Lecture 02 Using Logical Operators To Aid Searching

What Is A Search Engine Manual navigation of millions of web pages and thousands of newsgroups is impractical, A search engine is a catalogue of web pages, It stores details about site which searches can be carried out on, A search engine therefore is a user interface which allows you to search a huge database containing lists of web pages

and newsgroups, Search Engines comprise of three main components:

Sourcing the data Indexing and creating the database The search engine application

Page 4: Mr C Johnston ICT Teacher  G042 – Lecture 02 Using Logical Operators To Aid Searching

Search Engine Application Main user interface is written in HTML with a box for users to enter a search

string into, When the search button is pressed the search string is processed by a computer

programming language and a search is executed on the search engine database, The results are generated and displayed in a dynamic HTML page using a

mixture of programming code and HTML.

Machine WithInternet Connection

Search Engine Web server

Search Engine Request

Search Results Returned

Database Queried

Query Results

Search Engine Database

Page 5: Mr C Johnston ICT Teacher  G042 – Lecture 02 Using Logical Operators To Aid Searching

Searching Using Operators Searches can be made more efficient by pulling out key words and linking them together with Boolean operators. Operators Include:

AND(+) Finds pages with all the specified words in (not necessarily in order)

NOT(-) Finds pages that don’t include words

OR Finds pages which contain at least one of specified words

“ “ Finds pages with the exact phrase in

* Wildcard - not that useful (see example next slide)

Page 6: Mr C Johnston ICT Teacher  G042 – Lecture 02 Using Logical Operators To Aid Searching

Rules Type operators in CAPS with space between the keywords. When using + / - set watch where the spaces go….

+welding +process + welding + process +Saturn –car +Saturn – car

Spaces between keywords but not between keywords and operators.

Page 7: Mr C Johnston ICT Teacher  G042 – Lecture 02 Using Logical Operators To Aid Searching

Some Examples Use phrases, not single words and enclose in quotes. Finding websites about the the Roman invasion of Britain

Roman Invasion of Britain Pages Found: 665856 Roman Pages Found: 111130 “Roman invasion of Britain” Pages Found: 114

Use + for words that must occur and — for words that must not occur. Finding websites about the Amazon Rainforest

Amazon Pages Found: 204880 Amazon –book Pages Found: 106940 +Amazon –book +rainforest Pages Found: 10905

Think about word variations and plurals. education Pages Found: 485630 educat* Pages Found: 3484050(educational, educator, educated & education will appear)

Page 8: Mr C Johnston ICT Teacher  G042 – Lecture 02 Using Logical Operators To Aid Searching

Topic Exercise

Complete this topics reading: http://www.googleguide.com/ http://www.learnwebskills.com/search/engines.html

Download this topics worksheet and complete it.