Online Searching Basics -
Boolean Operators
Now that you have isolated your concepts and chosen your search terms, you must relate these terms to each other and create a search statement telling the database how the concepts are related. You do this by inserting logical operators between the concept terms you have just devised.
Use the Online Search Worksheet to map out your search statements and record which database system you have used.
AND, OR and NOT
There are three logical operators used in online searching: AND,
OR and NOT. These are the "Boolean Operators",
after George Boole, the mathematician who originated Boolean algebra.
Because Boolean Logic is one of the ways you "talk to the database",
understanding how Boolean Operators work is central to successful online
searching.
Example: I need to find articles about censoring the words in music.
AND - The
AND operator is used to combine two or more concepts. When you use the
AND operator, you require the database to locate articles containing a
combination of several different ideas.
lyrics AND censor
In the example, you
want both censor and lyrics to be present in the articles you
find. This retrieved set of articles is represented by the shaded area in the
center.
The information you need must contain the combination of both of these
ideas: AND narrows your search
OR - The OR operator is used for synonymous terms. OR tells the database that any of the search terms can be used interchangeably, since they all represent the same concept.
lyrics OR words in music
In the example, either lyrics or words in music will
be found. Therefore, both ovals are shaded: OR broadens your search.
NOT - The NOT operator excludes or eliminates a particular term from the search. It is rarely used. In the example, you might want information on any kind of music, except about music used in movies.
music NOT soundtrack
Some databases use other operators in addition to AND,
OR and NOT.
Click here to learn about common Proximity Operators.
Adapted from Hensley, R. B. and Hanson, E. Designs for Active Learning, ed. By Gail Gradowski, Loanne Snavely, and Paula Dempsey, 57. Chicago: Association of College and Research Libraries, 1998.
