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BOOLEAN, TRUNCATION AND WILDCARDs

BOOLEAN OPERATORS

Boolean operators (or "connectors") allow a database search to be narrowed, broadened or made more precise. In Boolean searching, sets are created by inserting an operator between search terms. There are three Boolean operators: AND, OR, and NOT.

A short description of each operator is given below. In the diagrams below, the shaded areas represent those records which would be returned.

AND

The AND operator is used for narrowing or focusing a search topic.
And specifies that both terms must be present on a record for it to be retrieved.
Example: teenagers AND violence.
TEENAGERS Vin diagram for Boolean Operator And VIOLENCE

OR

The operator OR is used for expanding or broadening a search topic.
By using the OR operator, the computer retrieves records that contain any of the terms. OR is used to include synonyms or related terms.
Example: teenagers OR juveniles.
TEENAGERS Vin diagram for Boolean Operator Or JUVENILES

NOT

The NOT operator is used to eliminate false hits.
By using NOT, the computer will retrieve records that contain the first term BUT NOT the second.
Example: teenagers not violence.
TEENAGERS Vin diagram for Boolean Operator Not VIOLENCE

To give a more meaningful example, matrix NOT reloaded NOT revolutions could be used to retrieve records concerning the first Matrix movie, while excluding the many records discussing the sequels. CAVEAT: Use NOT sparingly and give careful thought to the term to be excluded. A poorly chosen term will exclude good records with the bad!

Nesting

Multiple operators may be combined to create complex searches using nesting. Nesting involves enclosing search terms in parentheses to ensure operators are combined in the correct order. Always use the parentheses when mixing different opeators!
Example: (teenagers or juveniles) and violence.

TRUNCATION

Truncation expands the search to locate all words beginning with the same root . Example: teen* will return teen, teens, teenage, teenager, etc.)
Note that the actual sign used to truncate varies with different vendors/interfaces.

  • Cambridge Scientific Abstracts (CSA): use an *
  • EBSCOhost: use an *
  • FirstSearch: use a *
  • GIL Catalog (keyword/command only): use a ?
  • LexisNexis Academic: use a !
  • ProQuest: use an *

WILDCARD

A Wildcard is used in the middle of a word to match usually known variants of a term. A wildcard usually represents a single character, (e.g. wom?n finds women and woman).
  • Cambridge Scientific Abstracts (CSA): use a ?
  • EBSCOhost: use a ?
  • FirstSearch: use a #, or ? (Multi-character)
  • LexisNexis Academic: use a *
  • ProQuest: use a ?


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