AND, OR, NOT

These are Boolean operators, and they are the basis of mathematical sets and database logic.

• The three basic Boolean operators are: AND, OR, and NOT.
• They connect your search words together and can narrow or broaden your search results.

Why use Boolean operators?

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

Use AND in a Search to:

• connect two or more different concepts
• tell the database that ALL search terms must be present in the results list
• narrow your results - fewer results, and results can be more specific in subject coverage
• example: athletes AND doping

Use OR in a Search to:

• connect two or more synonyms or similar concepts
• tell the database that ANY of your search terms can be present in the results list
• broaden your results - more results, and results can be more general in subject coverage
• example: doping OR drugs

Use NOT in a Search to:

• exclude words from your search
• narrow your search, tell the database to ignore concepts not relevant to your search
• example:  doping NOT olympics

Subject Search

Keyword Searching or Subject  Searching?

Keyword searching - think of important words or phrases and enter them in to get search results. This is how we search using web search engines.

Subject headings  - words or phrases that describe what a book or article is about. Use subject headings to find additional, relevant items on the same topic.  Searching by subject headings is the most precise way to search databases.

Finding precise subject headings in a database can be a challenge.

To find subject headings for your topic:

• Start by doing a keyword search, using words and phrases that describe your topic.
• Browse the results and choose 2 or 3 that are relevant.
• Look at the Subject field and note the terms used (write them down).
• Redo your keyword search using these terms. Often they are hyperlinks that you can click. (See illustration below)
• Your results will be more precise than your initial keyword search.

Another way to find subject headings:

• Look to see if the database has a thesaurus or subject terms tool to browse for subjects that match your topic (check the Help screens).

Truncation

Truncation allows you to include multiple word endings and spelling variations in your search.  

• To use truncation, enter the root of a word and put the truncation symbol at the end.
• The database will return results that include any ending of that root word.
• Examples: 
  teen* = teen, teens, teenage, teenager, teenagers
  genetic* = genetic, genetics, genetically
• Truncation symbols may vary by database; common symbols include: *, !, ?, or #.
  Check the database's help page for more information.