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Page 1: Boolean Logic Combining search statements using Boolean operators

Boolean Logic

Combining search statements using Boolean operators

Page 2: Boolean Logic Combining search statements using Boolean operators

Bolean Logic 2

Boolean searching - OR

In database searching OR expands a search by broadening the set. It is often used to combine synonyms or like concepts.

Example 1. Use Boolean logic to describe an ice cream lover with global tastes (the coloured area)

Strawberry OR chocolate OR vanilla

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Bolean Logic 3

Boolean searching - AND

In database searching AND narrows a search. It is often used for linking together

different concepts.

Example 2. Use Boolean logic to describe an ice cream lover who only eats ice cream which combines 3 flavours at the same time e.g. Neopolitan ripple (the coloured area)

Strawberry AND chocolate AND vanilla

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Boolean searching - NOT

In database searching, NOT is used to get rid of an unwanted concept.

Example 3. Use Boolean logic to describe an ice cream lover who won’t eat chocolate (the coloured area)

(Strawberry OR vanilla) NOT chocolate

But BEWARE! – you may also exclude relevant articles.

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Boolean searching - PARENTHESES

Parentheses define the order in which the concepts are processed.

– AND takes priority– OR is processed last

HAMBURGERS EGGS

SALMONELLA

Use parentheses to ensure terms are processed as intended

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Some examples

Example 4: Find information on the influence of eggs on salmonella food poisoning caused by hamburgers

• salmonella AND hamburgers AND eggs = food poisoning caused by both together

• (hamburgers OR eggs) AND salmonella = food poisoning caused by either

• hamburgers OR eggs AND salmonella = Do you want eggs and gastro with your hamburger, or

would you rather have fries?• (hamburgers AND salmonella) NOT eggs =

= only food poisoning caused by hamburgers (removing the confounding effect of having eggs at the same time)

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A more complex example

Use Boolean logic to describe:

Women who have breast cancer but have never

smoked

Women who have breast cancer and who are EX-

smokers

Breast Cancer

Ex-smokersWomen

Smokers

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Women who have breast cancer but have never

smoked

= (women AND breast cancer) NOT smokers

A more complex example

Ex-smokersWomen

Breast Cancer

Smokers

Ex-smokersWomen

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Breast Cancer

Smokers

Ex-smokersWomen

Women who have breast cancer and who are EX-

smokers

= women AND breast cancer AND ex-smokers

A more complex example

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Breast Cancer

Ex-smokersWomen

Smokers

Men who have breast cancer and who currently smoke

= (men AND breast cancer AND smokers)

NOT ex-smokers

Another complex example

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Reference

Reference: Henderson J & Strickland J. Ithaca College Library Research Guide: Boolean Logic. Accessed at: http://www.ithacalibrary.com/sp/subjects/boolean on January 24, 2010

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