[Note to potential instructors: This module includes assignments and lectures focused on specific library databases. Your institution's library may or may not have a subscription to these databases. If your institution's library subscribes to different, related databases, then you will need to tweak this section to reflect those specific databases.]

What does "Boolean" mean?

"Boolean operators" -- also referred to as "Boolean logic" or "Boolean searching" -- can be used in many of our research databases. Using Boolean operators can help databases give you more focused, relevant results. You will get some practice using these tools in this week's homework, so let's take a closer look.

“Boolean” is usually associated with algebraic logic. But librarians and other researchers use Boolean operators in databases to try to drill down to the handful of useful articles in a database that might have 10 million not-so-useful articles in it.

Here's a short video (2:52 mins) on how Boolean operators work in databases:

Boolean operators

In short, Boolean operators are built-in tools within each database -- and even in search engines like Google! -- that allow you to broaden or narrow your search. Boolean searching involves using the built-in operators AND, OR, NOT to combine search terms in a database.

AND = used to combine separate topics or concepts together, like "violence" AND "video games"
OR = used when you need synonyms or similar words used to describe a similar topic or concept, like searching for either the phrase "capital punishment" OR "death penalty" in the same search
NOT = eliminates words in a search, like "world wide web" NOT spiders

The image below shows the built-in Boolean operators and shows a search in the Academic Search Complete database. Let's say you're searching for information about childhood diabetes and the connection with junk food. You might try searching using the Boolean AND and OR in a search that looks like this:

"childhood diabetes" OR "type 1 diabetes"
AND ("junk food" OR "fast food")

And here's what that search looks like in the Academic Search Complete database:

Sample search in Academic Search Complete using Boolean operators

Bonus search tips

Bonus search tip #1: Why did I put quotation marks around all those phrases, like "junk food"? That way, those two words, junk and food, are searched together as a phrase, rather than as separate words. This search tip works on almost every library database, as well as search engines.

Bonus search tip #2: Do you have to capitalize the Boolean operators of AND, OR, and NOT? Usually, the answer is yes (but it can depend on the specific database). The reason for why they are usually capitalized is that the Boolean operators act as codes, so when the words are capitalized, the computer knows to use them as codes and not to search for the actual words of and, or, and not. I also automatically capitalize AND, OR, and NOT if I am using them in a search, as that also visually helps me separate what I am searching for and keep things straight in my head.

Seeing Boolean operators everywhere!

Now that you know that Boolean operators are, you will start noticing them in a lot of search engines and library databases.

In Academic Search Complete -- a database which houses newspaper articles, magazine articles, and journal articles -- you will see that all of your searches will likely make use of one of more of the boxes shown in the image above. Using this kind of advanced search and combining search terms is the best way to narrow your topic and find information in these structured databases. Finding the right words, called "keywords" or "search terms," can be a challenge, but once you learn how to use these tools, the search just becomes a normal part of the research process.

After you've practiced searching with Boolean operators, click "Next" to learn more in-depth info and tips for three library databases, CQ Researcher, ProQuest, and Academic Search Complete.

Video source: "How do Databases Work? Keywords and Boolean Logic" by SanJacLibrary Video Help, Standard YouTube License
Tutorial sources: "Searching Effectively Using AND, OR, NOT" and "Advanced Boolean Searching" by Colorado State University Libraries
Except where otherwise noted, the content in this module by Tacoma Community College Library is licensed under CC BY SA 4.0

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