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Advanced Research: Boolean Operators

This guide is for MSJC students and advanced researchers and features topics such as strategic browsing, finding data and research tips to make your research process more efficient.

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 pieces of information to find what you're looking for.
    • Example: second creation (title) AND Outliers and Gladwell (author) AND 2008 (year)
  • Boolean operators can be used in search engines like Google, as well as library databases!

Search Order

Databases return results from the commands you enter. Be aware of the order in which words are connected when using Boolean operators: 

  • Databases usually recognize AND as the primary operator, and will connect concepts with AND together first.
  • If you use a combination of AND and OR operators in a search, enclose the words to be "read" together in parentheses.

Example:  people AND (success OR successful)

Example: pollution AND (water OR air)


Using AND

Use AND in a search to:

  • narrow your results, telling the database that ALL search terms must be present in the resulting records
  • Example: cloning AND humans AND ethics

NOTE:  In many, but not all, databases, the AND is implied. 

  • While this may seem to make searching easier, the terms may not be connected together in the way you want.
  • For example, this search: successful people is translated to: people AND successful. The words may appear individually throughout the resulting records.  Note also, that the search may retrieve parts of your search terms such as "success" from successful
  • You can search using phrases to make your results more specific by using double quotes: Example:  "successful people" AND "high achievers". The results will display the words as they appear together.

Using OR

Use OR in a search to:

  • broaden your results, telling the database that ANY of your search terms can be present in the resulting records
  • connect two or more similar concepts (synonyms)
  • Example: teenagers OR adolescents OR youth OR "young adults"

Using NOT

Use NOT in a search to:

  • narrow your results, telling the database to ignore concepts that may be implied by your search terms
  • exclude words from your search
  • Example:  pets NOT dogs