Boolean Operators
Using Boolean Operators: combining keywords in different ways can yield much better results for database (and Internet) research. There are three standard words which, when added to keywords, can dramatically improve the results. These so-called Boolean Operators are AND, NOT, and OR. Each has a specific function:
AND – used to join two or more keywords, this tells the computer that you only want documents in which all of the keywords appear.
NOT – used to exclude unwanted subject matter (added after the desired keyword list), this word prevents documents with unwanted subject matter from being listed in the results.
OR – used with two or more words, this operator allows the database to find any result that has either of the words; both keywords do not have to be in the document (opposite from AND).