Boolean logic allows you to combine search terms. Boolean operators are AND, OR and NOT. Most of the databases have advanced search where boolean operators are installed between search fields so you do not have to write the operators yourself.
AND narrows down your search results
AND operator tells the database that all your search terms must occur in the result. This reduces the number of search results. For example, when searching for materials that discuss both renewable energy and attitudes towards it, you combine the search terms with AND operator: renewable energy AND attitudes
OR broadens your search results
OR operator tells the database that at least one of the search words, but not necessarily all, must occur in the results. This increases the number of search results by giving the database alternatives. You can use OR to search for synonyms, for example green OR renewable OR sustainable. You can also combine related terms, for example wind power OR solar power, acronyms or broader and narrower terms.
NOT excludes all the records that include the chosen search term
NOT operator tells the database that the chosen search term cannot be included in the search results. This reduces the number of search results. Be careful when using NOT as it might leave out some relevant results. Example: renewable energy NOT wind power
See video on how to use Boolean operators to improve your search results.
Video: BethelUnivLibrary
It's possible to combine several Boolean operators. You can think of alternate terms for all of your search words, combine them with OR, and then combine these groups with AND. You get the widest possible search result by combining regular words (key words) with subject terms from thesauri.
If you write the operators yourself, use parentheses to specify the order in which the search terms are interpreted. Terms within parentheses are read first. For example: (green OR renewable OR sustainable) AND (energy OR power) AND (attitudes OR views). Without the parentheses most databases will read terms combined by AND first, which will change the search result.
See how to combine search terms in Finna advanced search.
Use term truncation or wildcards to include various word endings and spellings in the search result. Truncation or wildcard is marked with an asterisk (*) or a question mark (?) depending on the database you are using. Wildcard is useful for example when using search terms in English, as British and American English spellings vary, like in words organization vs. organisation, analyze vs. analyse etc.
Please check in the database instructions that you are using the right symbol. Many databases use automatic truncation and truncation symbols are not needed.
In Turku UAS Finna, the ? symbol substitutes one letter and * symbol substitutes none, one or more letters of the search term.
Use phrase search if you want to search for an exact phrase (two or more words in a specific order). Search engines search phrases marked with quotation marks in the order and form that are given.
Use quotation marks around the words for example "social media" and "management models".
Many databases offer phrase search functions such as "this exact phrase".
Narrow down your search with different ways:
Google, too, is a database, and like other databases it understands Boolean logic. You can improve your search results by using the retrieval techniques discussed above, such as Boolean operators and quotation marks. Please note that with Google you should use a minus sign instead of NOT to exclude a word, for example solar power -wind power
You can also use Google's advanced search option to improve your results. Advanced search can be found in Settings > Advanced search (see bottom of the page).
Advanced search has search fields where operators are automatically added between search words, so you do not have to write the operators yourself:
Advanced search also offers many options for narrowing your search, such as searching a specific site or domain, or filtering results by usage rights.
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This guide aims to support Turku UAS students and staff in searching information. It is a major part of the study material in the Information Skills Online Course.
Finding an interesting publication can help you come up with ideas for new searches:
Contact Library at the Turku University of Applied Sciences by email library@turkuamk.fi.
We are happy to help you!
This publication has been licensed with the Creative Commons Attribution 4.0 International license, unless otherwise stated.