Advanced searching involves using boolean operators, multiple terms, and filters to capture as many relevant results as possible, and to narrow results to those truly relevant.
The most common boolean operators are OR, AND, and NOT.
Note: Implementation varies across databases; to increase your chances of success, capitalize the above boolean operators—it isn't always necessary, but it won't hurt.
Other operators include double quote [""] and parenthetical [()] enclosure, and the asterisk [*], question mark [?], and minus operator [-].
Double quote enclosure allows you to require matching for an exact word or phrase.
A search for "bull horn" will return very different results than a search for bull horn.
Parenthetical enclosure allows you to override the order of operations; in boolean search, OR typically processes before AND, and AND typically processes before NOT.
A search for (continental AND plate) OR shelf will return very different results than a search for continental AND plate OR shelf.
The asterisk and question mark serve as a wildcard operators.
The question mark allows for one variable character.
A search for b?ll should return results that include the strings ball, bell, bill, boll, and bull—but not baall.
The asterisk allows for any number of variable characters, or no variable characters at all.
A search for continen* should return results that include the strings continence, continent, continental, and continents.
A simple search with boolean operators might look like:
continental AND plate OR shelf NOT "continental breakfast"
Library catalogs and databases often enable subject, topic, or author keyword searching.
Subject or topic terms are often stored in controlled vocabularies: these lists of terms and their definitions prepared and maintained by subject experts, and experts in the field of library and information science. The uniform nature of controlled vocabularies facilitates both searching and browsing.
Author keywords are terms chosen by authors when preparing work for publication, and can make it easier to discover resources—particularly when only an abstract is available, or when full-text searching is not enabled. Author keywords are not required to conform to existing controlled vocabularies, and for this reason, browsing for author keywords may not return as many results as expected, or may not be an option.
To search by subject in most databases, select Subject, Topic, or Author Keyword as the search type. To browse by subject, look for hyperlinked terms that appear under Subject or Topic headings in the resource record.