|
| |
Using Boolean Connectors
The words AND, OR, and NOT are known as Boolean connectors or sometimes logical operators. When searching databases they indicate how concepts relate to each
other. Use them to broaden or narrow your search by combining words or phrases.
Each Boolean operator has a specific meaning when used
as part of a search.
| |
Action |
Examples |
| AND |
The AND operator means
both words must be present. Use it to combine
two ideas which are both important. |
tractors and safety
violence and classroom
alcohol and pregnancy |
| OR |
The OR operator means
either word can be present. Use it to include
synonyms or alternate terms in your search. |
adolescent or teenager
female or woman
sex or gender |
| NOT |
The NOT operator means
a word should not be present in the search results. Use it with
caution since you can easily eliminate items you want. |
television not cable
cancer not mice
crime not murder |
| Nesting |
By combining operators you can fashion
a search for a very specific topic. Usually this is done by nesting,
e.g. placing certain terms in parentheses. |
(hogs or pigs) and market
(sex or gender) and pay
(cancer and fat) not mice |
The AND operator tells a computer system that both terms are important and must be included in your search results. It is used to narrow
a search.
| A keyword search
for: |
Retrieves: |
| child and abuse |
child abuse, abuse of the child, child sexual abuse,
etc. |
| homeless and teenagers |
homeless teenagers, teenagers who are homeless, teenagers
among the homeless, etc. |
When you enter two or more words without any connectors, each
computer system is programmed to make certain assumptions about what you
mean.
For example, in some databases the system assumes you mean AND.
In others the system assumes the words are next to each other, and you
must type AND or your search will match only the exact phrase
you entered.
| A keyword search
for: |
In |
Searches for: |
| trade unions |
CLICnet, EBSCO, CSA Illumina |
the phrase "trade unions" |
| Gale (InfoTrac) |
the words "trade" and "unions"
within 4 words of each other and in either order |
| ONEsearch |
trade and unions |
Use the OR operator to expand your search by including alternative
terms or variations in spelling.
- In most systems OR must be typed out in your search.
| To search: |
In: |
Type search as: |
| women or female |
CLICnet, all databases |
women or female |
| women or female |
| domestic violence
or wife abuse |
CLICnet, EBSCO, CSA Illumina |
domestic violence or wife abuse |
| Gale (InfoTrac), ONEsearch |
"domestic violence" or "wife abuse" |
You can use the NOT operator to exclude a word or phrase
from your search. BE CAREFUL--it is easy to
exclude useful items when trying to get rid of unwanted items. NOT is
most useful when there are alternative meanings of a search word.
For
example, "life support" can refer to astronauts or the terminally ill,
and is a good place to use not. AIDS not HIV would be an inappropriate
use of not, since many books and articles would discuss both conditions.
| To
search for: |
In: |
Type the search
as: |
| television not cable |
CLICnet, all Databases |
television not cable |
| prescription drugs and cost not Canada |
CLICnet, EBSCO, CSA Illumina |
prescription drugs and cost not canada |
| Gale (InfoTrac), ONEsearch |
"prescription drugs" and cost not canada |
Nesting, e.g. placing search terms in parentheses, is a
method of telling the computer system the order in which to process a your search terms. Use nesting for complex
searches using both AND and OR operators. Usually, you will place terms
to be ORed together in parentheses and the ANDed terms after
the parentheses.
Examples of nesting search terms
| To
search for: |
In: |
Type the search
as: |
| cancer in mice or rats |
CLICnet, all Databases |
(mice or rats) and cancer |
| cancer or neoplasms in mice
or rats |
CLICnet, all Databases |
(mice or rats) and (cancer or neoplasms) |
|
