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Using Boolean Operators

Venn diagram with the overlapping section shaded to show the boolean AND The AND operator narrows a search, retrieving only records containing both term(s). AND is used to narrow a topic to a specific aspect.

Example: anorexia AND "college students"
Venn diagram with all sections shaded to show the boolean OR The OR operator broadens a search, retrieving records that contain either term, but not necessarily both. It is used to combine synonyms or related concepts.

Example: anorexia OR bulimia
Venn diagram with only one section shaded to show the boolean NOT The NOT operator also narrows a search by removing all records that contain a particular word or phrase.

Example: anorexia NOT bulimia

The NOT operator is rarely used. It often screens out useful records.

Key Search Techniques

Quotation Marks

Using quotation marks in a search tells the database that you are looking for an exact phrase. Because of this, you only need to use quotation marks for a concept that is two or more words. For example if you were researching Social Security, using quotation marks ["social security"] would tell the database that you only want search results where Social Security appears as a phrase.

Without the quotation marks, the database actually reads your search as [social AND security]. This is an important concept to remember. Library databases will interpret strings of terms without any quotation marks or Boolean operators as being connected by the term AND. For example a search for [climate change glaciers] is translated by the database as [climate AND change AND glaciers]. This could return search results that are unrelated to your information need.

Truncation and Wild Cards

Truncation refers to shortening a word or eliminating characters in order to pick up variant terms in a database. Symbols are used for truncation. The most common symbols are the asterisk (*), the question mark (?), the pound sign (#), or a dollar sign ($). These symbols vary from database to database but are often indicated on a database's "Help" page. Examples of truncation:

  • child* - includes child and children
  • disab* - includes disabled, disability, disabilities
  • environment* - includes environment, environments, environmental, environmentalist, etc.

Wildcards are used for internal truncation. This will replace a single character in a search term. This is useful if a word has a letter difference between American English and British English or if a word is irregularly pluralized. The symbols used are different from regular truncation, but can be determined on a database's "Help" page. Examples of using the wildcard:

  • wom?n - includes woman and women
  • colo?r - includes color and colour