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Literacy and APA Resources

Boolean Operators

Boolean operators are commands that most databases use to connect or eliminated keywords in a search. The three primary Boolean operators are AND, OR and NOT. They must be capitalized in a search to be recognized as a command. 


AND retrieves records that include all the search terms. It will be used to narrow your search and combine search terms. 

Diabetes AND insulin
Length of stay AND costs 
on AND falls 



OR retrieves records that contain at least one of your search terms. It will be used to broaden your search.

Diet OR exercise 
Nurses OR nurse assistants OR nurse aides
Dementia OR delirium



NOT retrieves records that contain your first term but exclude your second term. This eliminates unwanted search terms from your query. It will narrow your search. NOT is recommended sparingly because relevant material may be eliminated.  

Blunt trauma NOT penetrating trauma 




Many databases use parenthese for complex or nested Boolean searches differently. Here are some tips:

  • Databases usually recognize AND as the primary operator. Put it first. 
  • Parentheses, (), can be used to encapsulate OR statements. (elderly OR aged OR senior ).
  • Put your primary search term first. 

Type 2 Diabetes AND (diet OR oral medication 

Salaries AND (Emergency medical technicians OR paramedics )


Most databases do phrase searching. If you can't find the exact phrase you are looking for try putting it in quotes. Note the database will only retrieve the words in between the quotes.  

"faces pain scale" 
"McGill Quality of Life Questionnaire"




Use the asterisk wildcard character (*) to include alternative forms of words. It can only be used at the end of a word. 

Japan* retrieves Japan or Japanese
Nurse* retrieves nurse or nurses
Nurs* retrieves nurse or nurses or nursing