boolean.htm

How to use Boolean Operators

The boolean operators AND, OR, and NOT describe the logical relationships between words or groups of words in a search strategy. Use your keywords in combination with these operators and you will be able to retrieve items more relevant to your topic.

Operator	Description	Diagram
AND	Using the AND operator narrows your search by retrieving only those records containing all terms. The AND operator requires that both the terms be in the same record. Example: Searching for tidal waves AND tsunamis retrieves records that contain both tidal waves AND tsunamis
OR	The OR operator broadens your search by retrieving all records which contain either or both terms. Example: Searching for tidal waves OR tsunamis retrieves records that contain either tidal waves OR tsunamis OR both.
NOT	The NOT operator excludes records containing a particular term as well as records containing both terms. Example: Searching for tidal waves NOT tsunamis excludes all records that contain tsunamis. *Use NOT with caution; it could eliminate records you want.

AND

Use AND to retrieve records containing both search terms: all terms must be in each record retrieved.
Use AND to narrow our search and retrieve fewer records.
Use AND for keywords listed in differenct columns of your search strategy

Use OR to retrieve records containing either or both search terms.
Use OR to broaden your search and retrieve a greater number of records.
Use OR for synonyms.
Use OR for keywords listed in the smae column of your search strategy.

NOT

Use NOT to retrieve records containing the first search term but not the second.
Use NOT to exclude certain items from your search.

Different Boolean Operators can be combined in a single search statement. When entering a search statement that has both the AND and OR operators, use parentheses around the terms combined with OR, so that the comuter processes them first.

Example: (tidal waves OR tsunamis) AND earthquakes