Boolean Logic refers to the words " AND, OR, NOT " and their intended usage with manipulating databases to either add, include, or subtract populated information from a data set. In other words, Boolean Logic refers to the logical approach (AND) instead of the arithmetical approach (+) to retrieve information from any database that contains data sets. The arithmetical approach refers to using symbols to convey addition as opposed to the logical sense which uses words.
The importance of using Boolean Logic when searching through databases is that it allows you to have control over what information the database will populate through your search in order to increase the efficiency and relevancy of your results.
Below you will find examples of each of the instances when you would use Boolean Logic and the results they would generate.
When a researcher such as yourself includes the Boolean operator "AND" into a database search field box, you may assume that because of the definition of the word "and" meaning adding together, you may get back more populated results.
This is a wrong assumption to make, in reality, using the Boolean operator "AND" will actually populate less data but the data populated will be more refined. Using the "AND" Boolean operator will tell the database to search for any information that contains ALL of the search criteria. For example, searching in a database for the terms (Ducks AND Geese) will populate articles/information that ONLY contain BOTH Ducks AND Geese.
Below is an example of the number of search results populated by entering "ducks AND geese" into the search field in the database EBSCOhost. Compare these results with the results of "OR" and "NOT" in the following sections.
The search of "Ducks AND Geese" retrieved 6,525 results. The database only pulled the articles that have BOTH ducks AND geese within an article.
Another also very common Boolean Operator is "OR". "OR" is often used when you want as much information as possible from the two inputted search terms regardless of other words those inputted search terms might be connected to.
In the same manner that the Boolean Operator "AND" may be confusing to beginners, "OR" has a similar misconception. Most individuals believe when we use "OR" that we want one search term or the other but not necessarily both. The truth to "OR" as an operator is that databases will populate data that contains either search terms or both. Look to the ven-diagram at the top of the page to see how using "OR" will populate data. For example, searching in a database for the terms (Ducks OR Geese) will populate information/articles that contain either ducks, or geese, or both.
Below is an example of the number of search results populated by entering "ducks OR geese" into the search field in the database EBSCOhost. Compare these results with the results of "AND" and "NOT".
The search strategy of "Ducks OR Geese" contain 202,458 results. There are more results than the search with the "AND" because the database is getting all articles that have ducks, geese, ducks AND geese.
Finally, our last Boolean Operator that we will be covering is "NOT". "NOT" is an operator designed to exclude a search term in order to help refine the data pulled from a database. Most of the time, using the operator "NOT" will help reduce the number of records and data pulled from a database. This is helpful when trying to limit the populated data or to make sure the database doesn't confuse your term with another similar term. For example, searching in a database for the terms (Ducks NOT Geese) will populate the information that contains the search term Ducks but will omit those that contain the search term geese. This is helpful when you only want information about ducks and not about geese even though both species are related to each other.
Below is an example of the number of search results populated by entering "Ducks NOT Geese" into the search field in the database EBSCOhost. Compare these results with the results of "AND" and "OR".
The search strategy of "Ducks NOT Geese" yielded 142,111 results. These results are less than the "OR" search strategy because the database is getting rid of results that have geese in them.
An important note to remember is that the Boolean Operators each have their own order when it comes to how the databases process their requests. This is a helpful tip when you begin to use more complicated search combinations with multiple Boolean Operators in each search. However, it is still important to learn this information now in order to familiarize yourself with the order as you begin your search strategies.
The order of how databases process Boolean Operators: