Boolean Operators
Boolean operators are words (AND, OR, NOT) that let you expand or narrow your search parameters when using a database or search engine. You can use these words alongside keywords to refine your search.
| Boolean Operator | Function |
|---|---|
| AND | Provides results that contain all keywords. Using AND between search terms will narrow your results. |
| OR | Provides results that contain either (or both) keywords. Using OR between search terms will broaden your results. |
| NOT | Provides results that contain the first keyword but not the second keyword. Using NOT between your search terms will narrow your results. |
Combining Searches
Nesting
Nesting is a way to combine several Boolean operators into one comprehensive search statement. Use parentheses ( ) to separate keywords when using more than one operator. Generally, databases process the search in the order of AND, OR, NOT. Searches within parentheses are performed first and operations proceed from left to right.
Example: (fruit) AND (apple OR orange)
Search results will be in the shaded region of the Venn diagram
Phrase Searching
Phrase searching allows users to search phrases rather than containing a set of keywords in random order. Each database uses different symbols to search a phrase.
| PubMed | OVID | Cochrane | Embase | Web of Science | EBSCOhost | ProQuest | Scopus | Nexis Uni |
| "double quotation marks" | NO quotation marks needed |
"double quotation marks" but NEXT when using truncation |
'single quotation marks' | "double quotation marks" | "double quotation marks" |
"{double quotation marks and curly brackets}" Tip: "{double quotation marks and curly brackets also used for truncation and wildcards}" |
"double quotation marks" for loose phrasing {curly brackets} for exact phrasing |
"double quotation marks"
|
How to Construct a Search String
