Database Search Tips: Boolean operators

Boolean operators form the basis of mathematical sets and database logic.

• They connect your search words together to either narrow or broaden your set of results.
• The three basic boolean operators are: AND, OR, and NOT.

Why use Boolean operators?

• To focus a search, particularly when your topic contains multiple search terms.
• To connect various pieces of information to find exactly what you're looking for.
• Example:
  second creation (title) AND wilmut and campbell (author) AND 2000 (year)

Using AND

Use AND in a search to:

narrow your results

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.

For example, Google automatically puts an AND in between your search terms.

Using OR

Use OR in a search to:

connect two or more similar concepts (synonyms)

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.

Using NOT

Use NOT in a search to:

exclude words from your search