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Help for Students>Search Tips>Boolean Searching
Boolean Searching
An effective way to search for information on a database is to combine terms together. This logical process, which is the key to effective database searching, was originated by mathematician George Boole. The concept of Boolean searching is the combining of two terms together connected by a Boolean operator--the words and, or, not.
The And Operator--Narrowing the Search
The Boolean operator and is used to narrow a search. For example, in searching for information about crime in Chicago, the periodical database searcher would use the search words Chicago and crime. The result is that only those periodicals articles that contain both of those words will be retrieved.
This diagram
represents a Boolean search using the and operator. Given the search
terms Chicago and crime, the database will be searched for instances
of the word Chicago, then for instances of the word crime, and
those articles that contain both terms, represented by the green oval above,
will be returned to the searcher. The returned articles are referred to as
hits.
The Or Operator--Broadening the Search
The Boolean operator or
is used to broaden a search. Sometimes a subject has several words that are
used to describe it. In that case, the or operator is used to make sure that
all relevant articles are caught in the search. For example, in searching
for information about teenagers, the periodical database searcher could use
the search words teenagers or adolescents . The result is that
articles that contain one of these word, or the other, or both words will
be retrieved. This will result in a large number of hits, some of which will
not be useful.
This diagram represents a Boolean search using the or operator. Given the search terms teenagers or adolescents, the database will be searched for instances of the word teenagers, then for instances of the word adolescents, and for articles that contain both words. All of the above will be returned to the searcher.
The Not Operator--Excluding
Unwanted Information
The Boolean operator
not is used to exclude unwanted articles. For example, in searching
for information about Cherokee Indians, but not wanting information on Cherokee
jeeps, the periodical database searcher would use the search words Cherokee
not jeeps. The result is that only those periodicals articles that contain
the correct use of the term Cherokee will be retrieved:
This diagram represents a Boolean search using the not operator. Given the search terms Cherokee not jeeps, the database will be searched for instances of the word Cherokee, then for instances of the word jeeps, and for articles that contain both words. Only the articles that appear in the blue oval above will be returned to the searcher.
The following are some links to websites that provide additional information
on Boolean Searching:
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