Boolean operators are words (or, and, not) used to connect search terms to expand (or) or narrow (and, not) a search within a database to locate relevant information. Boolean operators are also called logical operators or connectors.
It is helpful to diagram the effects of these operators:
women or females
|Or retrieves records that contain any of the search terms. It expands the search. Therefore, use "or" in between terms that have the same meaning (synonyms) or equal value to the search.|
women and media
|And retrieves records that contain all of the search terms. It narrows or limits the search. Therefore, use "and" in between terms that are required to make the search specific.|
image not weight
|Not eliminates records that contain a search term. It narrows or limits the search. Therefore, use "not" in front of a term to ensure that the search will not include that term. Warning: Some databases use "and not" instead of "not." Check the database help screen.|
- Most databases allow for a symbol to be used at the end of a word to retrieve variant endings of that word. This is known as truncation.
- Using truncation will broaden your search. For example,
bank* will retrieve: bank or banks or banking or banker or bankruptcy, etc.
- Databases and Internet search engines use different symbols to truncate. In general, most of the Library's databases use the asterisk (*) ; however, the exclamation point (!) is used in LexisNexis. Check the database help screen to find the correct truncation symbol.
- Be careful using truncation. Truncating after too few letters will retrieve terms that are not relevant. For example:
cat* will also retrieve cataclysm, catacomb, catalepsy, catalog, etc.
It's best to use the boolean operator "or" in these instances (cat or cats).
Some databases allow for wild cards to be embedded within a word to replace a single character. For instance, in InfoTrac, you can also use the question mark (?) within a word to replace a character. For example:
wom?n will retrieve woman or women