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Advanced Search Techniques


Boolean Operators

Boolean operators use AND, OR, NOT to limit or expand a search. (Note the capitalization. Many databases require operators to be in all caps, as do search engines like Google, which also allows for Boolean based searches.)

  • AND narrows a search by requiring the results contain both of the search terms connected by AND.

In other words, the search results will contain search term X and search term Y.

  • OR broadens a search and is usually used when searching related or similar terms.

In other words, the search results will contain search term X or search term Y or both.

  • NOT narrows searches by excluding sources with a specified search term.

In other words, the results will not contain search term X.

Boolean operator searches can be simple, e.g., Moose AND Elk; Moose NOT Elk. Or they can be more complex and nuanced when combining operators and use parentheses, e.g., (Caribou AND Elk) NOT Moose; (Moose OR Elk) NOT Caribou.

Simple Boolean Operator Example

In this very broad the Music Index search pictured below, the results will contain sources that reference jazz or blues and, in either case, will also reference Chicago.

In this search the words and Boolean operators "jazz OR blues AND Chicago."

Using Parentheses with Boolean Operators Example

To make even better use of Boolean operators, you can use parentheses to nest query terms. In the search pictured below, the results will include sources that address jazz AND New Orleans or blues AND Chicago.

This search groups the words and Boolean operator "Jazz AND New Orleans" with parentheses and "blues AND Chicago" with parentheses. Then uses the boolean operator "OR" between the two groups.