A keyword search is sometimes called a "Boolean search" and is a commonly used method of searching for specific information in a database. This search technique allows you to retrieve all records from a database containing a particular word or a combination of words. Such a search typically generates many results that may or may not be relevant to the user's query. To obtain more useful results, techniques such as Boolean operators, truncation and nesting can be used.
Boolean Operators
·
When performing a keyword search, the words "and,"
"or" and "not" are known as Boolean operators. Some search
engines allow the substitution of symbols such as the plus sign (+) in place of
"and" and the minus sign (-) to denote "not."
Using Boolean operators in a search query generates results that
are more specific to your needs. For example, the query "milk and cookies
and chocolate" will retrieve only documents containing all three words. On
the other hand, "milk or chocolate or cookies" will broaden the
search, retrieving all documents with one or more of these words. The query
"milk and cookies not chocolate" will retrieve all results containing
both milk and cookies but documents that contain the word chocolate will be
excluded.
Truncation and Nesting
·
Truncation allows the user to search for all terms with the root
word. Different search engines use different symbols for truncation, but the
asterisk is quite commonly used after the word to symbolize truncation. For
example, 'comp*' will generate results with words like computer, computing,
comptroller, compete, competition, competitive and competitor.
Some search engines allow the use of parenthesis to make groups
of your search words. This technique is called nesting. For example,
"English (British or American)" will generate results with the word
"English" and at least one of the two words, "British" and
"American." Nesting helps maintain the logic of the Boolean search
and is often used when the terms have similar in meanings.
Wild Cards
·
A wild card can be used when searching for alternate spellings.
It usually replaces the letters within a word that has variable spellings. For
example, "organiation"
will generate results with the word "organization" (the American
spelling) and "organization" (the British spelling.) Different search
engines recognize various Boolean characters but the most common are the
question mark (?), the asterisk () and the exclamation mark (!).