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ENG W240 Community Service Writing

On This Page

  • Why Use Boolean Operators?
  • Boolean Operators
  • Boolean Operators (video)
  • Searching Databases (video)
  • Too Few Results?
  • Too Many Results?
  • Subject Terms
  • Database Search Fields
  • Phrase Searching
  • Truncation
  • Nesting
  • Wildcards
  • More Resources

Why use Boolean operators?

Most library databases use Boolean operators (ANDOR, and NOT). 

Use them to narrow or broaden search results.

  • AND for records that include both terms (narrows search)
  • OR for records that include either term (broadens search)
  • NOT to exclude irrelevant concepts (narrows search)


Iran AND China AND (energy OR petroleum OR oil) 

Adapted from SAIS Library, Johns Hopkins Univ. "Database Search Tips" Guide

    Boolean Operators

    Using AND:

    • narrow results
    • ALL terms must be in each search result

    Note: in most, but not all, databases, the AND is implied. For example, Google automatically puts an AND in between search terms.

    Example:  renewable energy AND China

    Using OR:

    • connect similar concepts (synonyms)
    • broaden results (ANY of the terms can be in the search results.)

    Example:  renewable energy OR solar OR wind


    Using NOT:

    • exclude words from search
    • narrow the search

    Example:  peacekeeping NOT United Nations

    Adapted from SAIS Library, Johns Hopkins Univ. "Database Search Tips" Guide

    Boolean Operators

    Searching Databases

    Overview of database search tips.
    From Yavapai College Library. 

    Too Few Results?

    Don't give up! Reassess your search strategy.

    Possible Reasons:

    1. Choice of Search terms
    Choosing the right search terms is key.

    • Experiment with related terms.
    • In databases Subject Terms can help you identify keywords.
    • Use OR to search for multiple related terms simultaneously. (e.g., policy OR law)

    2. Too Many Search Terms
    Database can be picky about search terms. Be selective.

    • Begin with one of two search terms that best represent your topic. Then add other terms as needed.
    • Avoid long phrases and empty words like “the” and “how.”

    3. Too Many Limiters
    If you limited the search (e.g., by date or search field) remove limiters and reassess.

    4. Narrow Topic
    Highly specific topics may be too narrow for finding results. Try a broader related topic first. 


    • Narrow search: Bloomington Indiana AND environmental policy

    • Broader search: United States AND state government AND environmental policy

    5. Database Choice
    Different databases focus on different topics. View Resources by Subject or Ask a Librarian.

    Too Many Results?

    Narrow your search. Your initial search results can help.

    1. Add additional keywords.

    • TIP: In databases Subject Terms can help you identify more narrow topics and keywords.

    2. Choose more narrow search terms.


    • Broader term: law
    • Narrower term: "environmental law"

    3. Use limiters. (e.g., search fields like title or abstract, publication date, format type).

       In OneSearch see options under Refine Search.

    4. Search for a short phrase with quotation marks. 


    • "environmental law"
    • "enviornmental justice"

    Subject Terms

    Subject Terms can help you identify effective keywords. Most databases list Subjects in their search results.

    For example, in OneSearch

    1. Do an initial search. 

    2. Under Refine Search click on Subject.

    Database Search Fields

    Records in library databases are made of "fields." Fields can help narrow your search.


    • author
    • title
    • journal title
    • abstract
    • publisher
    • date/year of publication
    • subject/descriptor
    • all text (searches the full text, if available)

    Improving Search Results with Fields

    • Most databases automatically search by keyword (looking for the term anywhere in the record).

    • Limit the field for a search term to narrow the results. 

    • Fields are usually in drop down boxes.

    • If the database has a single search box with no drop-down menu, look for an "Advanced Search" option.


    Adapted from SAIS Library, Johns Hopkins Univ. "Database Search Tips" Guide

    Phrase searching

    Use quotation marks or parentheses around search words to search for a phrase. 
    (Otherwise most databases will find records that include both terms, but not necessary the terms as a phrase.)


    "middle east"
    "united nations peacekeeping forces"
    "civil society"

    Adapted from SAIS Library, Johns Hopkins Univ. "Database Search Tips" Guide


    Truncation broadens your search to include variant word endings and spellings. Enter the root of a word and then the truncation symbol.


      elect* = election, electoral, elections
      econ* = economy, economic, economics, econometric, economique
      politi* = politics, political, politician, politique, politische

      The most commonly used truncation symbol is an asterisk (*)
      A exception is LexisNexis Academic, which uses an exclamation mark (!).

      Adapted from SAIS Library, Johns Hopkins Univ. "Database Search Tips" Guide


      Nesting is the use of parenthesis to put search words into sets. Use nesting with AND, OR, or NOT, 

      success AND (education OR employment) 

      (records will contain the word success, AND either the word education OR the word employment)

      Nesting is often used when search terms have similar meanings:

      education AND (employment OR jobs)


      ? Wildcards are similar to truncation, but substitute a symbol for just one character.


      wom?n = woman, women

      democrati?ation = democratisation, democratization

      defen?e = defence, defense

      19?? = any  number between 1900 and 1999

      The most commonly used single wildcard symbol is a question mark. Some exceptions:

      If in doubt, check the help screens of the database you're using.

      Adapted from SAIS Library, Johns Hopkins Univ. "Database Search Tips" Guide

      More Resources