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Contents
- OR operator
- AND operator
- NOT operator
- Using Parentheses to Express Correct
Search Logic
OR Operator
OR - Any one of the terms are present (more than
one term may be present).
fruit OR vegetables
fruit OR vegetables OR cereal
OR - is
often used to broaden a search by linking together a number of synonyms.
cars or automobiles / marijuana or pot or cannabis
/ euthanasia or assisted suicide
AND Operator
AND - All terms are present. AND is the
best way to narrow down your search by limiting your results to only
those resources (articles or books) which deal with your chosen words.
rivers AND salinity
dairy products AND export AND europe
NOT Operator
NOT - The first term but not the second is
present.
fruit NOT apples
Using Parentheses to Express Correct Search Logic
Order of
precedence of Boolean operators is: AND, NOT, OR. That
is, an AND operation will be performed before an OR operation if both
operations are included in a query, unless parentheses are used to override
priority of search operators. Expressions in parentheses are processed first.
(foxes OR rabbits) AND pest control
The statement in parentheses - 'foxes OR rabbits' - is processed first.
If parentheses were omitted:
foxes OR rabbits AND pest control
The AND operation - 'rabbits AND pest control' - is processed first.
