Searching with Boolean Operators - Help Sheet


Boolean logic defines logical relationships between terms in a search. The Boolean search operators are and, or and not. You can use these operators to create a very broad or very narrow search.

Notes:

The following table illustrates the operation of Boolean terms:

AndOrNot
Each result contains all search terms.Each result contains at least one search term.Results do not contain the specified terms.
The search heart and lung finds items that contain both heart and lung.The search heart or lung finds items that contain either heart or items that contain lung.The search heart not lung finds items that contain heart but do not contain lung.

When a single Find field is displayed, you can enter search terms in the Find field, and combine with AND, OR, and NOT. (For example, Roosevelt NOT Franklin.)

Boolean Search on Basic Search Screen

When Guided-Style Find fields are displayed, you can enter search terms in each Find field, and select AND, OR, and NOT from the Boolean drop-down lists.

Boolean Search on Guided Style Find Fields

With longer search strings, you can combine many terms in a search with the AND operator, which will narrow your search results. For example, heart AND lung AND bypass AND artery will provide a more focused search than heart AND lung OR bypass OR artery.

To make even better use of Boolean operators, you can enclose search terms and their operators in parentheses to specify the order in which they are interpreted. Information within parentheses is read first, and then information outside parentheses is read next. For example, (heart OR lung) AND bypass will return different results than heart OR lung AND bypass.

Using Booleans and Parentheses

To make even better use of Boolean operators, you can use parentheses to nest query terms within other query terms.

You can enclose search terms and their operators in parentheses to specify the order in which they are interpreted. Information within parentheses is read first, then information outside parentheses is read next. For example,

When you enter (mouse OR rat) AND trap, the search engine retrieves results containing the word mouse or the word rat together with the word trap in the fields searched by default.

If there are nested parentheses, the search engine processes the innermost parenthetical expression first, then the next, and so on until the entire query has been interpreted. For example,

((mouse OR rat) AND trap) OR mousetrap

Using Booleans When Phrase Searching

When Boolean operators are contained within a phrase that is enclosed in quotation marks, the operator is treated as a stop word. When this is the case, any single word will be searched for in its place.

See also:

How can I ensure that EDS searches that include unintended Boolean operators will return the appropriate results?



ID: 3883
Topic: Interface Features
Services: EBSCOhost Research Interface, EBSCOhost Canadian, EBSCOhost UK, EBSCOhost Aust/NZ
Link: http://support.epnet.com/knowledge_base/detail.php?id=3883
Updated: June 2014

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