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BOOLEAN, TRUNCATION AND WILDCARDs

BOOLEAN OPERATORS

Boolean operators allow a database search to be broadened or made more specific. In Boolean searching, sets are created by inserting a Boolean operator in-between search terms. There are three Boolean operators used: AND, OR, and NOT.

AND

The AND operator is used for narrowing or focusing a search topic. By using AND, BOTH terms must be present in each hit or record for it to be retrieved. If one of the terms is not in the record, that record will not be displayed. For example, the search: teenagers AND violence will retrieve records that contain both of these terms and omit records that only contain the word teenagers, shown by the shaded area on the diagram below.
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 either of the terms (or both). OR is used to include synonyms or related terms, for example: teenagers OR adolescents 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. For example, the search: 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. It is easy to exclude good records with the bad!
TEENAGERS Vin diagram for Boolean Operator Not VIOLENCE

"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, for example: (teenagers or juveniles) and violence. It is important to enclose the synonyms in parentheses! If you fail to "nest", the computer may combine the terms in the wrong way (boolean "and" processed first, hence our example becomes (juveniles and violence) or teenagers).

TRUNCATION

Truncation expands the search to locate all words beginning with the same root (e.g. teen* finds teen, teens, teenager, etc.)
  • 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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