Search strategies in most databases are built upon a foundation of Boolean Logic. Depending upon the search platform you may have different options for the construction of a logical search. Boolean Logic at its simplest consists of three basic terms:
Remember that searching a database to find articles is essentially a word matching process. The terms you put in your search will be compared to titles, subjects, indexes, abstracts, and sometimes full text of articles to determine if the article will appear in the search results.
Use AND to add conditions to your search. These terms must all be matched for an article to appear in your results.
When to use AND:
e.g. You are researching the impact of invasive lionfish on Caribbean reef ecosystems. Your initial search might look something like:
lionfish AND Caribbean AND reef AND ecology
Things to expect by adding conditions with AND:
Use OR to add alternative conditions to your search. At least one of the terms must be matched for an article to appear in your results.
When to use OR:
e.g. You are researching Red Drum which have various names, both scientific and common. Your search might look something like:
Sciaenops ocellatus OR red drum OR spottail bass OR redfish OR channel bass
Things to expect by adding conditions with OR:
Look at the subject categories assigned to an article in the article record. You may discover new terms that can be used as synonyms or alternative search criteria.
Use NOT to add exclusions to your search. These terms must not be present for an article to appear in your results.
When to use NOT:
e.g. You are interested in the impact of crude oil upon fish but not the use of cooking oil for frying fish. Your search might look like:
(crude oil AND fish) NOT (cooking OR vegetable OR olive OR palm OR sunflower OR corn)
Things to expect by adding conditions with NOT:
Depending upon the database, other search limiters may be available on the search screen, including:
Wild cards are used to add flexibility to your search terms. Available wild cards vary by database so it's worth looking at the help section to determine how they should be used
* The asterisk is used to substitute for zero or more characters within or at the end of a word
e.g. Reproduc* accounts for reproduce, reproduces, reproduced, reproducing, reproduction, and reproductive
? The question mark is used to substitute for a single character (not zero characters)
e.g. Reproduce? accounts for reproduces and reproduced, but not reproduce or reproducing
e.g. Reproduct??? accounts for reproductive and reproduction
$ The dollar sign is used to substitute for zero or one characters. (Web of Science database)
e.g. Colo$r accounts for color and colour (American English and British English)