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SOCY 122 ASO Section 700: Introduction to Academic Library Research

Connecting Keywords: Boolean Operators

Once you have identified the keywords and phrases that describe your topic, the next step is to connect them in a logical way that the database will understand - this is accomplished with the use of Boolean operators: AND, OR, NOTBoolean operators connect your search words together to either narrow or broaden your set of search results

Databases and search engines (such as Google and Omni) make use of Boolean logic. Understanding how databases interpret your keywords will allow you to execute more specific searches, thereby saving you time while retrieving more relevant results. Boolean operators allow you to focus a search, particularly when your topic contains multiple search terms or concepts.

In many databases the Boolean operators are built into the search boxes. A database's Help pages will indicate how to construct Boolean searches and which wildcard characters the database supports. In the next module, we will apply these search techniques to searching Omni for books.

Venn diagrams are helpful to visually illustrate how these operators can be used:

Using AND

Use AND in a search to:

  • narrow your results
  • tell the database that ALL search terms must be present in the resulting records
  • Example: women AND income

  • In many, but not all, databases, the AND is implied. 
  • For example, Google automatically puts an AND in between your search terms.
  • Though all your search terms are included in the results, they may not be connected together in the way you want.
  • For example, the search: < university students test anxiety > is translated to:  university AND students AND test AND anxiety. The words may appear individually throughout the resulting records.
  • You can search using phrases to make your results more specific.
  • For example:  "university students" AND "test anxiety". This way, the phrases show up in the results as you expect them to be.

Using OR

Use OR in a search to:

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

example of using OR between two keywords


Using NOT

Use NOT in a search to:

  • exclude words from your search
  • narrow your search, telling the database to ignore concepts that may be implied by your search terms
  • use NOT sparingly, if at all, because you could end up excluding useful search results (e.g. articles or books that discuss both concepts)
  • example: exercise NOT fitness

Nested Searching

Whenever you have more than one Boolean operator, such as AND and OR, in a search statement, it is necessary to separate them with parentheses. This is known as a "nested searching." Here's an example:

("social movements" OR activism) AND (twitter OR facebook OR "social media") AND occupy

Nested searching tells the database the proper order in which to search for the keywords. Operations enclosed in parentheses are performed first followed by the operators outside the parentheses.


Rules about phrase searching vary from database to database. Some databases require them (without them an AND would be assumed between each word in your phrase, or worse, the database wouldn't be able to interpret your search), others supply them for you. If there is a Help section in the database you are searching, it will indicate whether or not quotation marks are required. In Omni you must use quotation marks for phrases. For example:

"social movements"
"social media"

Wildcard Characters

The wildcard is an advanced search technique that can be used to maximize your search results in library databases.  Wildcards are used in search terms to represent one or more other characters.

The two most commonly used wildcards are: 

An asterisk (*) may be used to specify any number of characters. It is typically used at the end of a root word, when it is referred to as "truncation."   This is great when you want to search for variant endings of a root word.

For example: searching for educat* would tell the database to look for all possible endings to that root. Results will include educate, educated, education, educational or educator. Use the truncation symbol with caution. Depending on your topic, it may be better to use an OR. 

For example education OR educational.

A question mark (?) may be used to represent a single character, anywhere in the word.  It is most useful when there are variable spellings for a word, and you want to search for all variants at once.  

For example, searching for wom?n would return both women and woman.