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Using the LSCO Library: Search Strategies

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Boolean

View two tutorials: 3. Searching effectively using AND, OR, NOT 

                                   4.  Combining AND, OR, NOT (advanced)

Summary: Library databases generally handle connecting words AND, OR, NOT in these specific ways:

  • Use AND between words when both (or all) words must be in the results, for example: cats and dogs and birds                                             Result: ALL three of these words must be present in each search result. Using AND has the effect of narrowing search results.
  • Use OR between words when either (or any) of the words are needed in the results, for example: cats or kittens or felines                 Result: ANY of the three words are present in search results. Using OR has the effect of broadening search results. The best use of OR is whenever there are two or more words with similar meanings and any of these words will work in the search results.
  • Use NOT between words when a word is causing the wrong information and needs to be eliminated from search results, for example: cats not dogs                                                                                                                                                                                                            Result: The first word (cats) is present in each search result but the word following NOT (dogs) is eliminated from results, even if the first word (cats) was also present in that result. Use of NOT is tricky. You could eliminate something you want!  
  • When using two or three connectors: Use parentheses ( ) around words connected with OR when combining with AND and NOT, for example:(cats or kittens or felines) and (care or feeding) not birds                                                                                                          Result: Any of the words inside the first parentheses combined with any of the words inside the second parentheses are in the search results. All results containing the word following NOT (birds) is omitted no matter what other words are present.  This technique is called "nesting." It tells the search engine in what order to combine words.

This use of AND, OR, NOT is called Boolean logic, after George Boole, the mathematician who invented it. Most of the library databases (the library catalog, all Ebsco databases, and others) understand the use of AND, OR and NOT to connect keywords and phrases. Some databases behave differently, so check the help pages to see how they work.

Search Terms

After selecting a database that is appropriate for your topic or information need, figure out the best search strategy for your chosen database. Always read the database descriptions and view any tutorials provided.