Most databases do not treat multi-word phrases as a unit unless that phrase is placed within quotations. If you search for a phrase like social assistance without quotes, most databases will seek the words social and assistance regardless of where they appear in the title, abstract, or other part of the document description. Without quotes, you will get results that include social and assistance, but they may be in a different order or so far apart from each other that the results have no bearing on your topic.

In most databases, you will need to place quotations around two or more words that must appear in a specific order to be meaningful. If you are unsure if your database requires this, check the database help page. It is often found somewhere adjacent to the search box where you enter your key terms or in the page navigation bar.

Boolean Operators (OR/AND) are commands used in a database to communicate the relationship between specific words and phrases, and between the groups of words and phrases that constitute your search criteria. These commands enable you to combine dozens (even hundreds) of topic elements into a single search string.

It is best practice to capitalize the letters OR as well as AND because some databases will only interpret these as a command if they are capitalized. Throughout this section, we will be describing the commands as OR or AND, however, it should be assumed that the commands are capitalized in the examples throughout.

For example, the research question "How do street economies in North America supplement social assistance programs?" can be operationalized with key concepts, keywords, and Boolean:

What it does:

• Combines keywords used to describe the same concept. E.g., “street economies” OR “street economy” OR “micro entrepreneurship”
• Tells the database to find documents with any one of these phrases in its title, abstract, or other element of the document's description
• Expands your results

When combining two keyword phrases with OR, documents with either or both phrases will be retrieved.

What it does:

• Combines keywords used to describe different concepts. E.g. "street economies" AND Canada AND "social assistance"
• Tells the database to retrieve only the documents that include all phrases in their description (title, abstract, etc.)
• Narrows your results

When combining two keyword phrases with AND, only documents with both phrases will be retrieved.

When using both operators – AND with OR - you establish criteria that can be both broadly inclusive of synonyms while also being narrowly focused on specific concepts.

The following table and figure provide two ways of visualizing the combination of AND with OR operators to develop an advanced search.

See this as a database screenshot

When AND is used to combine two or more groups of keywords or phrases, only those documents with at least one keyword or phrase from each group will be retrieved.

When inputting your keywords into a database, you can input the keywords combined with OR for one of your concepts into each search box. Add additional search boxes for additional concepts. As you add another search box, the database automatically includes the AND between the search boxes.

The figure below Is a screenshot of an advanced search in the database Web of Science that illustrates each concept of our search in a distinct search box with OR between the keywords for the concept as well as AND between each search box.

Most databases will only look for the exact set of characters that make up your keyword. For instance, a search for the keyword economies will only locate the nine characters it takes to communicate that word. The database will not retrieve results described with the keyword variations, like economy or economic. To account for keyword variations in your search, you would need to include each spelling: economies OR economy OR economic.

Instead, you can use a technique called truncation where the asterisks or star symbol is placed at the end of the most consistent characters in your words to tell a database to locate different variations of a word: econom*. This tells the database to include in your search any word that begins with a specific set of characters.

The asterisk (or star symbol) is created by using the key command SHIFT + 8 (for both PC and Macs).

To use truncation effectively:

• Review each keyword and generate a list of possible variations
• For each word, determine how many of the initial characters of the word variations are consistent and when those characters diverge
• Apply an asterisk after the last common character

A wildcard is a character that can be used in many databases to account for keyword spelling variations:

• Neighbo?r: retrieves neighbour and neighbor
• Wom?n: retrieves women and woman

Adjacency operators allow you to specify that the words you are searching must be within a certain distance or proximity of each other.

This can be useful if your keywords are more meaningful the closer they are to each other in a document's description. For example, you may want to find a keyword phrase in an exact order like “street economies,” but you may also be interested in wording like “economies of the street.” Adjacency operators allow you to search for both possible contexts in one step.

The characters needed for adjacency operators vary by database, but some common ones include:

*Substitute the # with the maximum number of words that may appear in between.

For example, micro N/3 entrepreneurship would retrieve source with the following phrases:

• “micro entrepreneurship”,
• “micro-financed entrepreneurship”, and
• “entrepreneurship built through micro loans.”

Parentheses () can be used to group a set of keywords so they can all be subject to the same database operation (I.e. AND, OR, N/#, etc.)

For example, street N/3 (economies OR economy OR entrepreneurship OR business OR trade) retrieves sources that include in their description the word street as long as is no more than three words away from the keywords economies, economy, entrepreneurship, business, or trade. The brackets allow the database to apply the relationship represented by the adjacency operator N/3 to all words the brackets enclose.

You can use parenthesis to build complex searches that include multiple advanced search techniques. Let’s say you were exploring climate change as a concept, and you come up with the following keywords for your search:

• Emissions
• Global warming
• Climate change
• Climate pattern
• Climate variability
• Weather change
• Weather pattern
• Weather variability

The phrases “climate change”, “climate pattern”, “climate variability”, “weather change”, “weather pattern”, and “weather variability” should be searched using a proximity operator since there are similar terms used throughout.

However, the other keywords like “global warming” and emissions do not contain either climate or weather. So, we need to use parenthesis to combine these keywords in a logical manner.

You can place parenthesis around each set of keywords in your proximity operator search, then place parenthesis around your entire proximity search. Finally, include your additional keywords with Boolean OR. 

Final search string: (emissions OR "global warming" OR ((climate OR weather) N/3 (chang* OR pattern* OR variabilit* )))