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Searching: AND, OR and NOT - advanced

Make the most of advanced searching!

AND, OR, and NOT - constructing complex searches

If you think back to learning about mathematical equations, searching is a similar concept.

When you've considered what keywords to search with, now you need to think about the order the search engine might read them in.

Search elements to remember

  • Your search terms - keywords, or titles, or author names are the most common
  • Connecting words AND, OR and NOT
  • (Using parenthesis to group a search/concept)
  • "Using quotation marks to force a phrase/title"
  • Wildcards 

The examples below are specifically for using the BCU Library Search - other search engines and databases may use the above elements slightly differently.

Order of operators

In a basic sense, search strings are read LEFT to RIGHT.

"Star Trek" AND captain NOT kirk - this search will look for anything about Star Trek captains but not about Captain Kirk.

"Star Trek" NOT captain AND kirk - conversely, this search will look for anything relating to Star Trek, but not mentioning captains, but will then look for the word kirk - there may be resources which mention kirk but not the word captain, or there may be authors named Kirk.


Refining the search string

In maths, anything in parentheses (brackets) is read first in an equation. By using this concept in our search, we can really make the search work as intended.

"Star Trek" AND (doctor OR captain) - this will look for anything at all about doctors or captains, then apply the rest of the search L-R. So, it's looking for Star Trek and anything about captains or doctors.

This idea becomes more important the more complex our search string.

"Star Trek" AND doctor NOT (phlox OR crusher) - Now the search is beginning by looking for anything with the words "phlox" or "crusher", then L-R it's searching for anything with Star Trek and doctors, but then excluding those results containing Dr Phlox or Dr Crusher.

"Star Trek" AND (doctor OR captain) NOT (discovery OR "deep space nine") - This search is similar to the above one, and we're now concerned about doctors or captains, but we're not interested in either Discovery or Deep Space Nine.

Using the advanced search

The examples given on this page apply to typing a search string into the basic search box.

The Advanced Search tool allows you to build a similar search. Anything on a separate line is considered to be (in brackets).

advanced search set to any field contains "star trek" AND any field contains doctor OR captain NOT any field contains discovery OR "deep space nine"

The big value of the advanced search lies in the fields that can be selected. 

  • Select a field such as title or author ("any field" is default) 
  • Select how the search term is applied, for example "exact" ("contains" is default)




Searching is a skill to learn. Start off simple, and add new keywords, phrases or operators in to build the search further.

You may not get the results you want immediately:

  • Try different words/phrases that mean the same thing.
  • Try moving operators around or grouping different words in parentheses until you hit on the right combination.
  • Try a simple search but use some of the other brilliant features that most specialist search engines and databases have, such as subject filters! On the BCU Library Search, you can find these on the left-hand side of the results page.
  • Rather than construct one huge, complex search that covers multiple concepts, try more searches with fewer keywords. It's unlikely that you'll hit on one search that covers every aspect of your assignment brief - break it down and think about what you'd like to write before thinking about keywords for each section, paragraph or argument.

Finally - don't be afraid to ask for help! We're here 24/7 and are happy to help you learn how to search.

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