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. The other operators that can help you with your search are parentheses, quotes, and asterisk/truncation.
Test your Boolean knowledge with the little quiz at the end!
AND
AND retrieves records that include both the search terms. It can be used to narrow your search and combine search terms.
Diabetes AND insulin
Length of stay AND costs
Readmission AND falls
OR
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
NOT retrieves records that contain your first term but exclude your second term. This eliminates unwanted search terms from your query. It can narrow your search. NOT is recommended sparingly because relevant material may be eliminated.
Blunt trauma NOT penetrating trauma
Parentheses
Many databases use parentheses for complex or nested Boolean searches differently. Here are some tips:
Type 2 Diabetes AND (diet OR oral medication)
Salaries AND (Emergency medical technicians OR paramedics )
Quotes
Most databases do phrase searching. If you can't find the exact phrase you are looking for try putting it in quotes. This will make sure that when you are searching the database, the words within quotes are kept together. Note the database will only retrieve the words in between the quotes.
"faces pain scale"
"McGill Quality of Life Questionnaire"
Asterisk
Also known as truncation. Use the asterisk character (*) to include alternative forms of words. It can only be used at the end of a word.
Examples:
Japan* retrieves Japan or Japanese
Nurse* retrieves nurse or nurses
Nurs* retrieves nurse or nurses or nursing