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Search Techniques

Boolean logic is used to establish relationships between the words entered in a computer database search.  Most databases and many popular Internet search tools permit the use of Boolean logic or one of its variations.

There are three basic operators. These are generally represented by the words OR, AND, and NOT, though some databases utilize special characters instead of the actual words. There are also several other techniques such as: nesting, truncation, phrase searching, proximity searching, and using wildcard characters.

Consult the online help screens for instructions specific to a particular database. For Internet search engines, Search Engine Watch provides a summary of the types of searches allowed and the required syntax for all the major World Wide Web search tools.

OR
OR logic will retrieve files or documents that contain at least one of the terms in the search statement. For example, a search for dogs OR cats will retrieve documents concerning dogs and other documents dealing with cats. This type of logic is useful when searching for synonymous words or concepts such as: children or kids, movie or film, sun or solar. Using OR generally increases the number of files or documents retrieved by a search.

AND
AND searches and retrieves files in which all of the terms in the query are present. If you entered dogs AND cats as a search statement, you will retrieve only those documents containing both dogs and cats. No documents only concerning dogs or only concerning cats will be found. Here are some other examples: television and violence, drugs and athletes, clinton and impeachment.
Using AND reduces the number of documents retrieved because it is more precise. There are for instance, thousands of books, articles, or websites devoted to the subject of television. In the example above, you are assuring that you only retrieve those dealing with violence as it relates to television.

NOT
If you wish to avoid retrieving documents containing certain terms, you should use NOT logic. NOT excludes terms from the results. For instance, if you were looking for documents concerning dogs but did not want any mention of cats you would enter dogs NOT cats. Some uses of NOT would be: mexico not new (if you are interested in Mexico, the country, not the state of New Mexico), impeachment not clinton (information on the impeachment of Andrew Johnson not Bill Clinton). Using NOT also enhances the precision of your search and, thus, reduces the number of documents retrieved.

NESTING
You may combine more than one Boolean operator in a search string using a technique called nesting. This uses parentheses to signify which operation(s) the search engine should do first. Once the query contained in parenetheses has been completed, additional Boolean operators may be applied to the results. For example: (sun or solar) not eclipse, (mexico not new) and government, (kids or children) and (television and violence).

TRUNCATION
This type of searching is used to retrieve documents containing different forms of a word. Usually, a character such as an asterisk (*) is placed at the end of the root word. For instance, a search for teach* would retrieve: teach, teaches, teacher, teachers, and teaching.

OTHER SEARCH TECHNIQUES:
The following techniques are NOT available when using, our online Wizard catalog, but they are available on many other electronic databases.

PHRASE SEARCHING
Most of the popular Internet search tools permit some form of phrase searching. This option allows you to specify that your terms must appear adjacent to one another and in the exact order in which they were entered. This is helpful when looking for names of people or organizations. Many of the searchers use quotation marks (".") to define a phrase search. For example, "george bush" or "students against drunk driving."

PROXIMITY
Some databases allow you to use proximity searching to insist that the search terms appear close to one another within the document.

WILDCARD
This technique is similar to truncation in that it allows the insertion of a character to retrieve variant forms of that word. The difference is that the wildcard character may be inserted within the word. If the wildcard character for a particular database was "?", you could enter wom?n to retrieve documents containing both woman and women.

Remember:
Databases vary in how they treat the techniques outlined above. Always read the instructions and/or help screens for each database you use. If you need further assistance, ask a reference librarian for help.