Research Guides: Search Databases Like a Pro: Search using AND, OR, NOT

And, Or, and Not

Connector words, such as AND, OR, and NOT, are commonly used techniques for searching on the internet and databases.

Using AND in a search

Narrows your results
Tells the database that ALL search terms must be present in the resulting records
Example: cloning AND humans AND ethics

BEWARE: In many cases the AND is implied. For example, Google automatically puts an AND in between your search terms. Though all your search terms are included in the results, they may not be connected together in the way you want.
For example, this search: college students test anxiety is translated to: college AND students AND test AND anxiety. The words may appear individually throughout the resulting records.
You can search using phrases to make your results more specific. For example: "college students" AND "test anxiety". This way, the phrases show up in the results as you expect them to be.

Using OR in a search

Connects two or more similar concepts (synonyms)
Broadens your results, telling the database that ANY of your search terms can be present in the resulting records
Example: cloning OR genetics OR reproduction

Using NOT in a search

Excludes words from your search
Narrows your search, telling the database to ignore concepts that may be implied by your search terms
Example: cloning NOT sheep

Word Order

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:

If you use a combination of AND and OR operators in a search, enclose the words to be read together in parentheses.
Examples: ethics AND (cloning OR reproductive techniques)
(ethic* OR moral*) AND (bioengineering OR cloning)