mr c johnston ict teacher g042 – lecture 02 using logical operators to aid searching
TRANSCRIPT
Mr C JohnstonICT Teacher
www.computechedu.co.uk
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.
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
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
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)
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.
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)
Topic Exercise
Complete this topics reading: http://www.googleguide.com/ http://www.learnwebskills.com/search/engines.html
Download this topics worksheet and complete it.