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Questions tagged [three-valued-logic]

logic using true, false and a third undetermined value

What is it?

A three-valued logic is a logic in whic every variable or term can have three possible truth value. In practice it will be a value for meaning TRUE, a value for meaning FALSE, and a third value which means that the value is not known (unknown, undetermined).

For example, SQL implements a three-valued logic, interpreting NULL as unknown.

See also

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OData request that returns items not matching the filter

I am trying to compose a OData URL which will selects from a collection with a filter on a related collection with a one-to-many relationship. The filter requires the related collections items to all have a specific value for some property. To…
R. Schreurs
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Can anyone tell me why my case statement return null(good)

I have a query return null(good) with case statements,but when use where statement for each case, have records in output . select a,b,sysdate , CASE WHEN a IS NULL AND SYSDATE > b THEN 'O' WHEN a IS NULL AND SYSDATE <= b THEN 'W' …
user11462075
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Implementation of SQL's three-valued logic

Is there a module in any SQL implementation that checks satisfiability/validity of a formula in 3-valued logic? If so, is there an open-source one? My purpose is to evaluate the performance of such a module (if exists) on the specific task of…
Yoni Zohar
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Logical operations in modal three-valued logic (XOR, IMP EQV)

From my understanding, the modal quantifier possibly relaxes the behaviour of logical conjunction: (true) and (possibly false) => true (true) and (possibly unknown) => true (possibly true) and (possibly false) …
AlexDarkVoid
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SQL 'Or' operator. How does it work in the following scenario?

I've been working on optimizing a query and have ran into a situation that's making me question how I've always used SQL's OR operator. (SQL Server 2000 also) I have a query where the conditional (WHERE) clause looks something like this: WHERE…
JamesEggers
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