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Many databases offer the use of Boolean operators to join search terms together. While a funny sounding name, Boolean operators are important in how the database interprets your search. By knowing what they are and how they determine what results you will receive, you will be able to search more efficiently and effectively.

Boolean Operators

• AND - Use AND when joining non-related terms together, for example heart attack AND women. Using AND tells the database to include all of the search terms in your search string and will usually reduce the number of results retrieved. Note that you do not have to use AND to join two terms in a recognizable phrase, for example, glass ceiling, intensive care, etc. Use the short video below for how to use AND effectively in database searching.

• OR - Use OR to join terms that are closely related or synonymous, for example adolescents OR teenagers. Using OR tells the database to search for either one or both of your terms and thus will increase your result list. You will usually use OR in conjunction with an AND search; for example drug abuse AND (teenagers OR adolescents). If you receive too many results, you may be joining too many terms together with OR. Focus on the main concepts of your topic for a more effective search. View the short video below on how to use OR effectively in database searching.

• NOT -  Use NOT to exclude a term entirely, for example Miami NOT dolphins.

In addition to using AND, OR, NOT in searching, databases also have Limiters, that can further focus your search. Limiters tell the database to retrieve results according to a certain set of criteria.  Common, useful limiters are full text, peer review, and date range. Depending on the subject specificity of the database, limiters can also determine research interest, publication type, language, geography, and more.  There are a few different ways to employ limiters:

1. Apply limiters to your search at the outset, and edit as needed.  

2. Perform an initial search, view results, then apply limiters. 

Using the first scenario as an example, type your search terms in, then move to larger box below to select your limiters. This particular search will retrieve results on capital punishment that are full text, from peer reviewed journals, and have been published since 2010.

Using the second scenario as an example, type in your search terms and click Search. Limiters are available in the left column; once you choose a limiter, your results are automatically updated.  

The limiters of individual databases vary depending on if you are in basic search mode or advanced search mode. Normally you will see more specific limiters if you choose advanced search mode.