A database is a set of structured data held inside a computer, often paired with a search interface so users can find specific information. While each database is unique in their content, most follow similar rules when it comes to their structure and search accessibility. One of these rules is Boolean logic, which helps users define the relationships between search terms. Most databases use Boolean logic, whether they make it obvious or not.
See below for examples of basic Boolean logic and how to best use them when creating a search:
| Concept | Search term examples | Search results |
| AND |
"early intervention" AND disability "indigenous history" AND massachusetts
|
Both terms included in results
|
| OR |
impact OR effect coronavirus OR COVID |
One or both terms will be included in results
|
| NOT |
"lab grown meat" NOT "plant based meat" "George W. Bush" NOT "George H.W. Bush" |
One term excluded from results
|
Each database is unique, and will present search logic differently. Some will keep things extremely simple, some will include a wide variety of search options. You can find information on what kinds of logic and search shortcuts each database uses by finding the Search Tips or Help? section on the default or Advanced Search page.
Pub Venn is an app which visually represents search terms and their Boolean logic in the form of Venn diagrams when searching PubMed. PubMed is a free digital archive of biomedical and life sciences journal literature through the U.S. National Institutes of Health (NIH), so it is best used for medical/scientific research or for anyone wanting to better understand how Boolean searches work.
Google and Google Scholar may look like databases, but they are classified as search engines. Search engines do not organize books and articles in the same way a library database does. They are typically less precise and provide fewer relevant filters and search options for users. While Google Scholar is an academic search engine that indexes scholarly literature, it does not provide filters for full text or peer-review, both essential to the academic researcher. Additionally, Google underwrites each search using algorithms to anticipate your information needs. This can be helpful at the beginning of your research to gauge your interest in a topic or what kind of information is currently available, but can end up providing irrelevant results with little accountability.
Both Google and Google Scholar use Boolean logic and other search shortcuts common in databases in their regular and advanced searches. Instead of the typical AND/OR/NOT, Google describes what each of these mean in plain, simple language.
If the research question is "how does consumer perception of lab grown meat affect sales?", one could use the basic search in Google Scholar and use the bolded keywords (Google will ignore words like "of", "the", or "in", also known as stopwords), but the results may be too wide-ranging.
Simple search: 22,000 results
Using Google Scholar's advanced search/Boolean search, you have more control over search results - it allows you to define relationships between keywords and set appropriate parameters. With more control over results, you save time and effort in evaluating content irrelevant to your research topic.
"With all of these words" = AND (spaces between words are treated as AND)
"With the exact phrase" = searches phrases exactly as they appear - will put "quotation marks" around phrase)
"With at least one of the words" = OR
"Without the words" = NOT
Same keyword search, using Google Scholar Advanced Search: 907 results
