Boolean Operators – A Simple Guide With Examples

Boolean operators are vital tools when working with sources for academic writing. These operators, namely AND, OR, and NOT, help refine your search in databases and search engines, enabling you to find the most relevant resources effectively. In this guide, we’ll dive into the practical use of Boolean operators to enhance your research and source management skills. Below, we explain how to use Boolean operators in searches. Please read on for examples of how Boolean operators work.

Definition: Boolean operators

Boolean operators are logical connector words such as ‘and‘, ‘or‘, and ‘not‘. They make database searches more precise and save time by removing unsuitable results. These searches use Boolean strings, i.e., keywords joined with one or more logical operators.

Boolean operators and how to use them

Using Boolean operators can significantly reduce or expand the number of records returned. The targeted results save time. Apart from research, the technique is valuable in investigation and reviews.

Boolean Operator AND

Boolean Operator ‘AND‘ obtains results with two or more keywords. Both terms are in each result, so it narrows database searches. Thus, ‘dogs AND service animals’ would return information about guide dogs and police dogs, but not pet animals.

Boolean Operator OR

Boolean Operator ‘OR‘ returns at least one of the keywords, so it broadens a database search. ‘Ecology OR pollution’ would find results containing ecology (though not pollution), pollution (but not ecology), and both words in either order.

Boolean Operator Quotation Marks: ” “

Quotation marks specify the exact keywords contained within them. The search is more precise; results must include the phrase as a whole, i.e. the words together and in order. Searching for wild animals (without quotation marks) yields results with either word and both separately. In contrast, searching for “wild animals” returns articles with that exact phrase.

Boolean Operator Asterisk: *

We use the asterisk symbol to truncate a search word. The results contain variations of a root word.
Use the asterisk to find results that contain the keyword you entered and other words that begin with those letters. For instance, electr* would return for electronics, electrical, electricity, electrify, electrode, etc.

You can also use an asterisk at the beginning of a word. Results using ‘*electr*’ would also include hydroelectric, microelectronics, etc.

Boolean Operator Parentheses: ( )

Parentheses group keywords together. Database queries and search engines evaluate parenthesized Boolean expressions first, thus customizing the results.
In the above example, ‘(smoking or vaping) and arteries’ returns results containing: ‘smoking and arteries’, ‘vaping and arteries’, and ‘smoking, vaping & arteries’. However, it does not return ‘smoking or vaping’ when the word ‘arteries’ is absent.

More than one bracket is possible. Imagine you are looking for medicines or medical interventions for seizures and convulsions other than those due to epilepsy. The following search contains multiple brackets and all the Boolean operators:

How Boolean operators are used in databases

Search engines and database systems use Boolean operators slightly differently. They may require capitalized operators or use special punctuation.

Google’s advanced options increase accuracy by fine-tuning the keyword search.

• We use’+‘ for AND operations, so ‘World War +2’ would focus results on the Second World War.
• Conversely, we use the minus symbol ‘–‘ instead of NOT to exclude undesired keywords.

Computer programming languages also use Boolean operators.

Proximity operators

Finally, we use proximity operators to filter database searches based on the proximity of one keyword to another. This technique increases the relevance of results.

The three proximity operators and their functions are:

Database query formats vary; some may use a different notation to represent the above operators.