Boolean Operators
Boolean operators form the basis of mathematical sets and database logic.
- They connect your search words together to either narrow or broaden your set of results.
- The three basic boolean operators are: AND, OR, and NOT.
Why use Boolean operators?
- To focus a search, particularly when your topic contains multiple search terms.
- To connect various pieces of information to find exactly what you're looking for.
- Example:
second creation (title) AND wilmut and campbell (author) AND 2000 (year)
AND / OR
Use AND in a search to:
- narrow your results
- tell the database that ALL search terms must be present in the resulting records
- example: cloning AND humand AND ethics
The purple triangle in the middle of the Venn diagram represents the result set for this search. It is a small set using AND--the combination of all three search words.
Use OR in a search to:
- connect two or more similar concepts (synonyms)
- broaden your results, telling the database that ANY of your search terms can be present in the resulting records
- example: cloning OR genetics OR reproduction
All three circles represent the result set for this search. It is a big set because any of those words are valid using the OR operator.