Subjects: General Guides
Tags: research, tool

Combining Search Terms & Boolean Logic

You may combine search terms and fields using AND, OR, and NOT (Boolean logic).

AND: When you combine search terms with AND in a full-text search, your results contain everything in which both terms appear. Combining search terms makes your search results more precise. You can explicitly denote AND in the following ways: cat AND dog, cat && dog+cat +dog, (cat dog)

OR: Using OR between search terms allows to you find all items that contain either term. Using OR will search for items that contain either the word "cat", the word "dog", or both. For example: cat OR dog

NOT: Searches using NOT will only find items that do not contain the search term following it. NOT must be capitalized. To find all items with the word cat that do not contain the word dog, search for: cat NOT dog, cat -dog (Be sure to include a space before the dash, but not after). 

Grouping Combined Search Terms

Parentheses allow you to determine the order in which terms are combined. The search "currency reform" AND (russia OR "soviet union") will search for items that contain the phrase currency reform and that contain either russia or soviet union. Without grouping parentheses, the search is interpreted as "currency reform" AND russia OR "soviet union," which returns items containing either both currency reform and russia or containing soviet union. By using parentheses, you may control the grouping of search terms.

Additional examples:

  • (finch OR sparrow) AND exotic will search for items that contain the word exotic and either the word finch or the word sparrow
  • (birds OR butterflies) NOT sparrow will search for items that contain either the word birds or butterflies and do not contain the word sparrow
  • birds NOT (sparrow AND robin) will search for items that contain the word birds but do not contain both the words sparrow and robin
  • birds NOT (sparrow OR robin) will search for items that contain the word birds but do not contain either the word sparrow or the word robin