Mr C Johnston

1
G042 Lecture 02 Using Logical Operators To Aid
Searching

• Mr C Johnston
• ICT Teacher
• www.computechedu.co.uk

2
Session Objectives

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

3
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

4
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.

5
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 dont 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)

6
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.

7
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)

8
Topic Exercise

• Complete this topics reading
• http//www.googleguide.com/
• http//www.learnwebskills.com/search/engines.html
• Download this topics worksheet and complete it.