Boolean Operators connect keywords or concepts logically to retrieve relevant articles, books, and other resources.  There are three Boolean Operators:

• AND
• OR
• NOT

Using AND 

• Narrows search results
• Connects two or more keywords/concepts
• All keywords/concepts connected with "and" must be in an article or resource to appear in the search results list

Venn diagram of the AND connector

Example: The result list will include resources that include both keywords -- "distracted driving" and "texting" -- in the same article or resource, represented in the shaded area where the circles intersect (area shaded in purple).

Using OR

• Broadens search results ("OR means more!")
• Connects two or more synonyms or related keywords/concepts
• Resources appearing in the results list will include any of the terms connected with the OR connector

Venn diagram of the OR connector

Example:  The result list will include resources that include the keyword "texting" OR the keyword "cell phone" (entire area shaded in blue); either is acceptable.

Using NOT

• Excludes keywords or concepts from the search
• Narrows results by removing resources that contain the keyword or term connected with the NOT connector
• Use sparingly

Venn diagram of the NOT connector

Example: The result list will include all resources that include the term "car" (green area) but will exclude any resource that includes the term "motorcycle" (purple area) even though the term car may be present in the resource.

A library database searches for keywords throughout the entire resource record including the full-text of the resource, subject headings, tags, bibliographic information, etc.

Keywords:

• Natural language words or short phrases that describe a concept or idea
• Can retrieve too few or irrelevant results due to full-text searching (What words would an author use to write about this topic?)
• Provide flexibility in a search
• Must consider synonyms or related terms to improve search results
• TIP: Build a Keyword List

Example:  The keyword list above was developed to find resources that discuss how texting while driving results in accidents.  Notice that there are synonyms (texting and "text messaging"), related terms ("cell phones" and texting), and spelling variations ("cell phone" and cellphone).  Using keywords when searching full text requires consideration of various words that express an idea or concept.

Subject Headings

• Predetermined "controlled vocabulary" database editors apply to resources to describe topical coverage of content
• Can retrieve more precise search results because every article assigned that subject heading will be retrieved.
• Provide less flexibility in a search
• Can be combined with a keyword search to focus search results.
• TIP: Consult database subject heading list or subject headings assigned to relevant resources

Example 1: In EBSCO's Academic Search Complete, clicking on the "Subject Terms" tab provides access to the entire subject heading list used in the database.  It also allows a search for specific subject terms.

Example 2:  A subject term can be incorporated into a keyword search by clicking on the down arrow next to "Select a Field" and selecting "Subject Terms" from the dropdown list.  Also, notice how subject headings are listed below the resource title, providing another strategy for discovering subject headings used in the database.

Phrases

When a search term is more than one word, enclose the phrase in quotation marks to retrieve more precise and accurate results.  Using quotation marks around a term will search it as a "chunk," searching for those particular words together in that order within the text of a resource. 

Examples:

"cell phone"

"distracted driving"

"car accident"

TIP: In some databases, neglecting to enclose phrases in quotation marks will insert the AND Boolean connector between each word resulting in unintended search results.

Truncation

Truncation provides an option to search for a root of a keyword in order to retrieve resources that include variations of that word.  This feature can be used to broaden search results, although some results may not be relevant.  To truncate a keyword, type an asterisk (*) following the root of the word.

For example:

Limiters

Library databases provide a variety of tools to limit and refine search results.  Limiters provide the ability to limit search results to resources having specified characteristics including:

• Full text
• Resource type
• Publication date
• Language
• Geographic location
• Subject

In both the EBSCO and ProQuest databases, the limiting tools are located in the left panel of the results page.

                                                 EBSCO                                                     ProQuest

The short video below provides a demonstration of how to use limiters to refine a list of search results.

Fields

Each resource in a library database is stored in a record.  In addition to the full-text of the resources, searchable Fields are attached that typically include:

• Author
• Title
• Journal title
• Date of Publication
• Abstract
• Subject Headings
• Publisher

Incorporating Fields into your search can assist in focusing and refining search results by limiting the results to those resources that include specific information in a particular field.

In both EBSCO and ProQuest databases, selecting the Advanced Search option will allow Fields to be included in a search.

For example, in the Advanced Search option in EBSCO's Academic Search Complete database, clicking on the down arrow next to "Select a Field" provides a list of fields that can be searched within that database.  Select the field and enter the information in the text box to the left to use this feature.

Stop Words

Stop words are short, commonly used words--articles, prepositions, and pronouns-- that are automatically dropped from a search.  Typical stop words include:

• a
• an
• and
• the
• also
• but
• for
• in
• is
• of
• so
• which
• when
• was

In library databases, a stop word will not be searched even if it is included in a phrase enclosed in quotation marks.  In some instances, a word will be substituted for the stop word to allow for the other words in the phrase to be searched in proximity to one another within the text of the resource.

For example, if you searched company of America, your result list will include these variatons:

• company in America
• company of America
• company for America

Creating an Search String

This short video demonstrates how to create a search string -- keywords connected with Boolean operators -- to use in a library database search to retrieve relevant resources for any research assignment.