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Online/Distance Learning Library Orientation: Database Searching

This guide is intended for students enrolled in an online nursing program at PNW.

Database Searching

This page provides information on how to perform a simple database search using Boolean operators, keywords and subject headings.

Note: A strong search will use Boolean operators, keywords and subject headings.

Boolean Operators

Boolean operators are simple words (AND, OR, NOT) used to interpret research requests and retrieve relevant information from a database. Boolean operators are generally not case-sensitive.

AND-Adding AND to a search narrows that search by telling the database to only retrieve results that contain all of the terms connected with the word "and." 

OR-Adding OR to a search broadens that search by telling the database to include results that contain any of the terms connected with the word "or."  The Boolean OR is useful in combining keywords that represent a single concept.

NOT-Adding NOT to a search limits that search by telling the database to exclude results that contain any of the terms mentioned after the word "not." 

Keywords and Subject Headings

Keywords are words used to describe a topic.  Keywords are natural-language vocabulary.  That means they can come from any source and the database will look for these words anywhere within its records.

Subject headings are predefined words from a controlled vocabulary source such as a thesaurus.  These words were assigned to articles by subject-specialists. MeSH (Medical Subject Headings) is the controlled vocabulary thesaurus produced by the National Library of Medicine. MeSH is widely used to index/classify articles in nursing research databases. 

Important: Quotation marks around words will retrieve results with that exact phrase.


1. Go to the Medical Subject Headings thesaurus at Enter "heart attack" in the search box. View the term that has been selected and assigned by the United States National Library of Medicine (NLM) to describe articles about heart attacks.

2. Open the CINAHL Complete database from the library's homepage. Perform a new search for each of the following search statements. Note how many results are generated after each search.

  • "Cardiovascular Diseases" AND hypertension
  • "Cardiovascular Diseases" OR hypertension
  • "Cardiovascular Diseases" NOT hypertension
Search Tips:
  • Boolean operators and search terms are not case-sensitive.
  • You can perform a new search by clicking on the New Search located on the top of the page as shown below.

Library Liaison for Nursing Students & Faculty

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Marcia Keith
Student Union & Library Building: Rm 203-B
Subjects: Health, Nursing

About the Library

The library offers a wide range of online resources, including databases with various journals from which to choose articles and research studies.

To access your Library resources, please visit the homepage

Please consult your Library Liaison directly for research assistance.

If your Librarian is unavailable, please contact the Library's Reference desk at (219) 989-2676 or click on the CHAT WITH A LIBRARIAN link below to submit a question or see answers to frequently asked questions.

Library Hours

Library staff members are available to assist you during library hours