What are Boolean operators?

Boolean operators are words that can be used in a search string to combine or exclude words from the results list. This allows your to narrow or broaden your results, depending on your need. The three main Boolean operators are AND, OR, and NOT.

Using AND

Using AND in a search string:

• Narrows your results
• Tells the database you only want results that include all of the search terms

Example

Using the search string:

tourism AND sustainability AND Alaska

will only return results that include all three search terms. The Venn diagram below illustrates this search string. The only results returned are represented by the blue shaded area of the diagram where all three circles overlap.

Using OR

Using OR in a search string:

• Broadens your search
• Tells the database that you want results that include any of the search terms

Example

Using the search string:

tourism OR sustainability OR Alaska

will return results that include any of the three search terms, alone or in combination. The Venn diagram below illustrated this search string, The returned results are represented by the shaded area of the diagram which includes all portions of all three circles.

Using NOT

Using NOT in a search string:

• Narrows your search
• Tells the database that you don't want results that include certain terms

Example

Using the search string:

tourism NOT sustainability NOT Alaska

will return results that include tourism, but don't include either sustainability or Alaska. The Venn diagram below illustrated this search string, The returned results are represented by the shaded area of the diagram which only includes the portion of the tourism circle that doesn't overlap either of the other circles.

Using Boolean operators in combination

You can use multiple different Boolean operators in a search string to get a more specific results list.

Example

Using the search string:

tourism AND sustainability NOT Alaska

will return only results that include both tourism and sustainability, but don't mention Alaska.

Parenthesis

You can use parenthesis to help you make even more complex searches.

Example

Using the search string:

(tourism OR travel) AND sustainability

will return results that have either both tourism and sustainability or both travel and sustainability.