NexusDB

Specify a boolean value.

Syntax

<boolean term> ::=

Notes

       <boolean primary> IS NOT <truth value>

is equivalent to:

       NOT <boolean primary> IS <truth value>

Since SQL supports null values and predicates whose value can be UNKNOWN, a three-valued logic is used to evaluate boolean value expressions. The rules of this logic are summarized in the following tables:

Truth Table for the AND Boolean Operator

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Truth Table for the OR Boolean Operator

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Truth Table for the NOT Boolean Operator

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Truth Table for the IS Boolean Operator

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Examples

       SELECT studentID, studentName, city, state

       FROM students

       WHERE  city = 'Newport' AND state = 'CA'

       SELECT studentID, studentName, city, state

       FROM students

       WHERE  city = 'Newport' AND ( state = 'CA' OR state = 'RI' )

       SELECT studentID, studentName, city, state

       FROM students

       WHERE  ( city = 'Newport' AND state = 'CA' ) OR state = 'MA'

       SELECT studentID, studentName, city, state

       FROM students

       WHERE  NOT ( ( city = 'Boston' AND state = 'MA' ) OR state = 'CA' )

Conformance