Library Orientation for Nursing

Boolean logic is a building block of many computer applications and is an important concept in database searching. Using the correct Boolean operator can make all the difference in a successful search.

Why use Boolean logic? 

These databases are not intuitive like Google is. For example, if you search for Used cars for sale in Google, you will get results equivalent to the searches Used Toyotas for sale or Used SUVs for sale. With these databases, however, you will get exactly what you asked for. They won't give us information about used SUVs because we didn't ask for it. That's why it's important to have as many search terms as possible. 

There are three basic Boolean search commands: OR, AND and NOT. They each serve a different purpose. 

• AND searches find all of the search terms. For example, searching for dengue AND malaria AND zika returns only results that contain all three search terms. Very limited results.
• OR searches find one term or the other. Searching for dengue OR malaria OR zika returns all items that contain any of the three search terms. This returns a large number of results.
• NOT eliminates items that contain the specified term. Searching for malaria NOT zika returns items that are about malaria, but will specifically not return items that contain the word zika. This is a way to fine-tune results. 

Using OR:

OR tells the database that any of your search terms can be present in the resulting records. It can also connect two or more similar concepts (synonyms). Use OR to search for similar search terms or synonyms​. This will give you MORE results. 

Example: (bedsores OR pressure sores OR pressure ulcers)

​Using AND:

AND tells the database that all search terms must be present in the resulting records. Use AND to combine different search terms or search phrases. ​AND will give you LESS results.

Example: (bedsores OR pressure sores OR pressure wounds)​ AND (children OR pediatrics)

Using NOT:

NOT tells the database to ignore concepts that may be implied by your search terms. NOT will exclude words from your search. Note: sometimes AND NOT is used; this serves the same function as NOT.

Example: (bedsores OR pressure sores OR pressure wounds)​ AND (children OR pediatrics) NOT (outpatient)

Search Order and Parentheses:

Similar to math, search order and parentheses matter! Databases follow commands and return results based on those commands. Be aware of the logical order in which words are connected when using Boolean operators. Each different concept should be enclosed within its own set of parentheses.

For example:  dengue OR malaria AND zika can be interpreted as:

•  (dengue OR malaria) AND zika returns articles about dengue or malaria, that also discuss zika. Every item returned would mention zika, and either dengue or malaria. As the zika virus has only recently been a serious issue, this would limit the number of results.
• dengue OR (malaria AND zika) returns every article about dengue, or those that discuss both zika and malaria. Since dengue fever has been a concern for over 250 years, this search would yield different results. Every item about dengue would be returned, as would those that discuss both of the other two.

Using Quotation Marks:

If you're searching for a phrase rather than just a single word, you can group the words together with quotation marks. It prevents a phrase or group pf words from being split up will return only items with that exact phrase.

Instead of: (bedsores OR pressure sores OR pressure wounds)​ AND (children OR pediatrics)

Try this: (bedsores OR "pressure sores" OR "pressure wounds")​ AND (children OR pediatrics)

Using Asterisks:

Asterisks allow for truncation and will catch all endings of a word. Truncation instructs the database that it should search for the root of the word you have typed in and then retrieve any alternate endings. This is useful for searching for plurals without having to type out both the singular and plural in your search, but will find also find any other alternative endings. Note: not all alternative endings will be appropriate.

Instead of: (bedsores OR “pressure sores” OR “pressure wounds") AND (children OR pediatrics)

Try this: (bedsore* OR “pressure sore*” OR “pressure wound*") AND (child* OR pediatric*)