Boolean logic is worth using especially when the search problem cannot be described with one term. Boolean logic is a way of narrowing or expanding a database search by linking search terms with the connectors AND, OR and NOT. Boolean logic can be used when searching a library online catalogue or an e-resource, or when using the Internet search engines.
When using words of natural language for searching, truncation is advised. Truncation allows you to avoid long and complex search phrases with many different forms of words linked with connectors. Truncation is necessary when searching Finnish databases and using Finnish search terms, which usually have many inflected forms. Thesauruses can be helpful when trying to find the right words.
It is important to truncate the search term from the right point. If the word is truncated too early, the search results will contain irrelevant references.
Note that databases have different ways of marking truncation. The most common marks are * ? #.
Eg. emu* searches for "emus", "emulation", and "emulsion".
Nested searches are used to create more complex Boolean logic statements.
A search phrase in brackets will be executed first. Use brackets when you use different connectors in the same search string.
Use phrase searching if you have a search term which consist of more than one word. Putting quotation marks " " around the phrase forces the database to search for results where those words appear right next to each other, in the order you wrote them, and with no other words between them. Phrase searching is used with frequently used phrases.
Some databases allow searching for words in the same sentence or within three or four words of one another by using proximity connector NEAR. This increases the relevance of the results by ensuring that concepts are connected in the right context.
Note! Check that the search engine supports nested searches and proximity connectors.
Use the connector AND to retrieve references that must include all search terms. AND narrows a search by linking two or more terms. It is used to combine different ideas or concepts and to cover different aspects of the study area.
Search A AND B retrieves documents and references which contain both A and B.
Use the connector OR to link synonyms, related terms or broader and narrower terms. OR broadens the search.
Search A OR B retrieves references that may include either A or B or both.
NOT narrows the search by excluding undesired concepts. Use NOT with caution, as you may exclude relevant references as well. A safer way to exclude irrelevant references is to use limiters (year of publication, language, subject terms).
Search A NOT B retrieves references containing A and excludes B, but also references containing both A and B.