Most Library databases incorporate the use of Boolean logic (and, or, not) in the search "string". With some databases, the terms need to be entered; with others, the terms are available through drop down menu options.
Retrieves only the information located where two or more concepts intersect. The “and” operator requires that all of the terms are included in the search results.
Example: searching for the doping of silicon with boron = silicon and doping and boron
Think of it as meaning “also” or “too”. The “or” operator allows a search for synonyms, or concepts that are similar to one another.
Example: searching for three different substances, such as silicon, germanium and selenium, and any mention of any of the substances would be useful = silicon or germanium or selenium
is used to exclude a specific unwanted or unrelated topic. Although this operator is not used as often as the other Boolean Operators, it can be useful. The “not” operator requires that the term after the “not” be absent from the results.
Example: searching for “ion beam lithography” without any mention of the phrase “electron beam lithography” = "ion beam lithography" not "electron beam lithography"
For a visual depiction of each of these operators, take a look at Boolean Logic in Computer Searching
Many databases allow search refinements such as truncation, proximity, and field searching to allow more specific searching. Here are some descriptions and examples of some commonly used features.
Truncation: allows a word stem and variant endings to be searched. The most common symbols used are: * ? # These characters may also be used as wildcards. A wildcard might stand for multiple characters, one character only, be used at the end of a word, in the middle of a word or at the beginning. More than one wildcard may be used in a database, with differing actions. Check the help pages of each database to determine the applicable wildcard definitions.
If an * is defined as representing multiple characters at the end of a string of letters (truncation), then Engineer* searches for engineer, engineers, engineering.
Caution: if the word stem is too short, you will retrieve many words that are not of interest to you. Example: dop* searches for doping, dopant, dope as well as doppler.
Proximity (also known as phrase searching) allows more specificity on how close two words are in the text. Common commands include near and with, abbreviated with n and w respectively, and sometimes allow specifying the number of terms between two words. Forcing the database to search for two or more words right next to one another is a type of proximity searching, and is often enabled by placing the two words in quotations.
Field Searching allows specifying the part of the record in which the term is to be searched. Field codes vary between databases, so check the help pages for the particular codes used by the database you are searching.
Variations include using + to require terms and – to exclude terms from the results.