Boolean operators form the basis of mathematical sets and database logic.
Why use Boolean operators?
Use AND in a search to:
The purple triangle in the middle of the Venn diagram below represents the result set for this search. It is a small set using AND, the combination of all three search words.
Be aware: In many, but not all, databases, the AND is implied.
Use OR in a search to:
All three circles represent the result set for this search. It is a big set because any of those words are valid using the OR operator.
Use NOT in a search to:
Databases follow commands you type in and return results based on those commands. Be aware of the logical order in which words are connected when using Boolean operators:
These pages are based on a guide developed by the Massachusetts Institute of Technology (MIT) Libraries. They are used here under the creative commons (cc) licence. The original pages can be found here http://libguides.mit.edu/c.php?g=175963&p=1160724