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What are Boolean Operators?

Last Updated: Feb 03, 2017  |  41 Views

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The Boolean operators are three conjunctions (linking words) used by databases to link search terms together: AND, OR, & NOT.

These are the terms you use to combine separate search terms into a search strategy.

Each operator links terms together in a different way to the others, producing markedly different search outcomes.

The chart below indicates how each works:

 Operator   AKA  Principle

 Retrieval    Logic

 Results

 AND

 Selective  Combiner 

 Only retrieves records in which both  terms are present

 AND =  A+B,    A,B  Small retrieval but highly relevant to topic. 

 OR

 Non-selective  Combiner

 Retrieves records wherein both terms  are present, or either term is  present.

 OR =  A+B, A,  B  Large/massive retrieval but high percentage of irrelevant records
 NOT  Excluding  Operator  Only retrieves records wherein excluded term is not present

 NOT =
 A,
 A+B, B

 Eliminates every occurence of excluded  term, including records in which desired terms also appear.

For a rough idea of the type of search retrieval each operator garners, take two search terms, combine and search them with each operator in a database and note the size of your search results:

Example: internet, neutrality (database: Academic Search Complete; searched June 21, 2014)

 Search  Strategy

 Result  Tally   Explanation  Retrieval  Logic

 Internet  

    AND  

 Neutrality 

     778  Search result is small because only records in which both "Internet" and "Neutrality" are present are retrieved.  AND =  A+B,    A,B

 Internet

    OR  

 Neutrality 

     417,206    Search result is massive because every record in which either term appears (and both together) is being retrieved.   OR =  A+B, A,  B

 Internet

    NOT  

 Neutrality

     410,047    Search result is 7,159 records smaller than the OR search (above) because every occurence of  the term "Neutrality" has been eliminated from search results.  NOT =
 A,
 A+B, B

 

Neutrality

 

 7,159

 

 Searching the term "Neutrality" alone confirms that there are currently 7,159 records in  Academic Search Complete containing this term. Search 3 (above) elminated every record from its search result.

You can use Boolean operators to combine two terms into a simple search, or use several operators and multiple terms to create intricate and powerful search strategies.

If you need assistance building a search strategy using Boolean operators or simply finding the right search terms, please contact the Reference Desk at 903.566.7343 or at library@uttyler.edu.

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