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Module 1:
Using Boolean AND and OR in Library Catalogs and Databases |
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©2020 by Chris Niemeyer, University of Missouri-St. Louis.
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Module 1:
Using Boolean AND and OR in Library Catalogs and Databases |
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©2020 by Chris Niemeyer, University of Missouri-St. Louis.
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If you are a student, knowing simple 'Boolean logic' will help you search for information in library catalogs and databases with precision, speed and ease.
Boolean logic is a system that helps you arrange keywords to properly find information in these sources. Screen2 |
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We will demonstrate this search system using two Boolean 'operators' (sometimes called 'connectors').
These will be: AND and OR. Screen3 |
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Day-to-day communication provides some insight into Boolean logic.
Imagine you have dined at a restaurant. A waiter asks what you would like for dessert, and you reply: "I would like apple pie OR chocolate cake." Screen4 |
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Well ... which of the two deserts do you really want?
"I would like apple pie OR chocolate cake." Screen5 |
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But if you say:
AND "I would like apple pie OR chocolate cake." "I would like apple pie AND chocolate cake." the request becomes understandable. Screen6 |
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With this slight modification the waiter would understand that you want both types of dessert. Maybe a strange request, but also a comprehensible one.
"I would like apple pie AND chocolate cake." Screen7 |
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You know more about Boolean logic than you think because we all know how to use or as well as and in everyday speech.
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Knowing this, you should be able to employ Boolean or and and in library databases and catalogs for similar reasons.
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Below is the search line for a library catalog. Imagine you type-in the following
keyword search that uses Boolean or:
l
i
g
h
t
n
i
n
g
o
r
C
l
e
o
p
a
t
r
a
o
r
h
u
m
m
i
n
g
b
i
r
d
s
o
r
e
c
o
n
o
m
e
t
r
i
c
s
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This is an unusual keyword search since the terms appear to have NOTHING to do with each other.
lightning or Cleopatra or hummingbirds or econometrics
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Yet the search will retrieve a huge number of hits in most library catalogs - so many, in fact, that a catalog might only display the top 1,000 or so. Go to a library catalog and try it yourself if you don't believe it.
lightning or Cleopatra or hummingbirds or econometrics
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Why so many hits?
Using or between keywords means you are requesting that all terms be retrieved.
lightning or Cleopatra or hummingbirds or econometrics
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Faced with this literal request, the catalog returns EVERY record that contains just ONE of your keywords.
lightning or Cleopatra or hummingbirds or econometrics
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So, every record mentioning lightning will be retrieved, along with every record mentioning Cleopatra, along with every record mentioning hummingbirds, along with every record mentioning econometrics!
lightning or Cleopatra or hummingbirds or econometrics
A gigantic set of book records, most of which will have NOTHING to do with each other! Screen15 |
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But the situation is radically changed when one uses and between search terms....
lightning or Cleopatra or hummingbirds or econometrics
lightning and Cleopatra or hummingbirds or econometrics
lightning and Cleopatra and hummingbirds or econometrics
lightning and Cleopatra and hummingbirds and econometrics
and
and
and
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In such a case, the keyword search will almost certainly return zero hits! Go to a library catalog and try it yourself if you don't believe it.
lightning and Cleopatra and hummingbirds and econometrics
Why zero search results?... Screen17 |
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ALL keywords must be present in every single record whenever Boolean and is used exclusively between search terms. Boolean and narrows searches. Remember: we are searching for books in a regular library catalog.
lightning and Cleopatra and hummingbirds and econometrics
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Library catalog records for books can be pretty spare. They try to describe the content of a book as concisely as possible. They might link to the full-text of a book but they won't have the full-text themselves.
lightning and Cleopatra and hummingbirds and econometrics
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Knowing this, is is unlikely to find records in a library catalog for books about lightning, Cleopatra, birds of the family Trochilidae (hummingbirds were unknown to the Ancient Egyptians) and econometrics, a social science that uses mathematical modeling to understand economic activity.
lightning and Cleopatra and hummingbirds and econometrics
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Once more, Boolean and narrows a search so that all keywords MUST be present in every single record.
lightning and Cleopatra and hummingbirds and econometrics
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Just like in everyday speech, Using AND/OR in keyword searches produces quite different results depending on which of the two words you use.
lightning and Cleopatra and hummingbirds and econometrics
We will show an example of a helpful Boolean keyword search in the next module. Module finished! Screen22 |
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