1. Combining search statements using Boolean operators
Boolean Logic
Combining search statements using Boolean operators

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
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
Bolean Logic

4. 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.
Bolean Logic

5. Boolean searching - PARENTHESES
Parentheses define the order in which the concepts are processed.
AND takes priority
OR is processed last
SALMONELLA
HAMBURGERS
EGGS
Use parentheses to ensure terms are processed as intended
Bolean Logic

6. 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)
Bolean Logic

7. Use Boolean logic to describe:
A more complex example
Breast Cancer
Ex-smokers
Women
Smokers
Use Boolean logic to describe:
Women who have breast cancer but have never smoked
Women who have breast cancer and who are EX-smokers
Bolean Logic

8. A more complex example
Women who have breast cancer but have never smoked
= (women AND breast cancer) NOT smokers
Breast Cancer
Smokers
Ex-smokers
Women
Women
Ex-smokers
Bolean Logic

9. A more complex example
Breast Cancer
Smokers
Ex-smokers
Women
Women who have breast cancer and who are EX-smokers
= women AND breast cancer AND ex-smokers
Bolean Logic

10. Another complex example
Breast Cancer
Ex-smokers
Women
Smokers
Men who have breast cancer and who currently smoke
= (men AND breast cancer AND smokers) NOT ex-smokers
Bolean Logic

11. Reference
Reference: Henderson J & Strickland J. Ithaca College Library Research Guide: Boolean Logic. Accessed at: on January 24, 2010
Bolean Logic