- AND
If you want a document that contains all of your keywords, use the
capitalized word AND between keywords. The engine will only
find documents that have both words. Here's an example: Using the
search criteria 49ers
AND schedule would return all documents that contain
both words. Be sure to capitalize all letters in the word AND, otherwise
the search engine will treat it as a keyword, not as an operator.
If the left oval represents all documents containing the word 49ers
and the right oval represents all documents containing the word schedule,
the intersection of those ovals, the green area, represents all documents
containing both words. You can see how this operator is useful in
narrowing your results.
- OR
If you want to broaden your search to find documents that contain
either of the keywords, use the OR operator between words. This is
very useful when searching for terms that have synonyms. An example
is children OR kids,
which would return any document that had either of the words.
If the left oval represents all documents containing the word children
and right oval represents all documents containing the word kids,
the green area represents documents that contain either word or both
words. You can see how this operator broadens your search, obtaining
more results.
- NEAR
This operator is a more specific form of the AND operator. It ensures
that the document contains both terms and that they are located
near each other. In many lengthy documents, just using the operator
AND might not provide useful results as the two keywords may be located
in very different parts of the document and might not be related to
one another.
- NOT or AND NOT
Using the capitalized AND NOT preceding a search term eliminates
documents that contain that term. Why would you want to do this? If
you want to find information on Dieon Sanders and do not want documents
that include information relating to the Dallas Cowboys you could
use "Dieon Sanders"
AND NOT cowboys.
- Parentheses
The operators AND, NEAR, OR and AND NOT are powerful in their own right, but when used in conjunction with parentheses, they offer substantial control over the search logic executed by the engine. Parentheses are used in Boolean logic similar to the way they are used in a mathematical equation, limiting and ordering relations between variables.
Here's an example: If you want to find a Web-based Internet tutorial
you might use the search criteria Internet
AND (tutorial OR lesson). The
documents returned must contain both of the words Internet
and tutorial or Internet and lesson. Essentially,
the parentheses are used as they are for the distribution property
in mathematics--to distribute the keyword Internet to either
of the two "OR" words inside the symbols.
The most common use of parentheses is to enclose
two possible keywords separated by an OR operator and then linking
those enclosed/possible keywords with other criteria using AND. However,
there are times and instances where the reverse arrangement might
prove useful. For example, if you were looking for information on
gun control you might want to use "gun control" OR (legislation
AND gun), which would return documents with the words "gun
control" or documents containing the word gun and the word
legislation.
You can further refine the search. Since the
word "law" is a synonym of legislation you can even nest one set of
parentheses inside another to distribute gun to either legislation
or law and while we're at it, truncate "law" with an asterisk
to also distribute gun to the variation--laws.
Here's how it would look: "gun control"
OR (gun AND (law* OR legislation)). Note that each left side parentheses
must be paired with a right side one somewhere in the Boolean expression
or the search engine will get confused (see how stupid they are!).
+require and -exclude
Some engines offer a variation of the Boolean operators AND and
NOT. A + symbol preceding a word (with no space between) requires
that the word be present in documents. A - symbol preceding a keyword
ensures that the word is not present in returned documents. Note that
all words that must be in the document should be preceded by a + symbol,
even the first word. Here's an example: +fraud
+election ensures that fraud is also in all the documents.
Use the Site
