Biconditional - sql, PL-SQL Programming

Biconditional - SQL

The biconditional p ↔ q can be expressed in Tutorial D by p = q and the same is true of SQL. The question then arises as to whether, in SQL, p = q is equivalent to (¬p ∨ q) ∧ (¬q ∨ p). This matter is investigated in the truth table of Figure.

1394_biconditional.png

Figure: SQL p = q ≡ (¬p ∨ q) ∧ (¬q ∨ p)

As you can see, the equivalence does hold in SQL, but only because SQL treats unknown as not equal to-i.e., not the same truth value as-itself ! This treatment of p = q is consistent with the general rule that applies when NULL is an operand of a comparison in SQL.

Posted Date: 1/18/2013 4:19:28 AM | Location : United States







Related Discussions:- Biconditional - sql, Assignment Help, Ask Question on Biconditional - sql, Get Answer, Expert's Help, Biconditional - sql Discussions

Write discussion on Biconditional - sql
Your posts are moderated
Related Questions
CLOSE Statement The CLOSE statement allows the resources held by a cursor variable or open cursor to be reused. No more rows can be fetched from the cursor variable or closed

Tautologies: Above given table allows us to read the truth of the connectives in the next manner. Just expect we are looking at row three. It means this says that, if there P

Positional and Named Notation You can write the actual parameters when calling a subprogram, using either positional or named notation. That is, you can point to the relationsh

Assigning and Comparing Collections One collection can be assigned to other by an SELECT, INSERT, UPDATE, or FETCH statement, an assignment statement, or by a subprogram call. A

Negation (NOT, ¬) - SQL There are three rows instead of just two. As you can see, ¬ p is defined as in two-valued logic (2VL) when p is either true or false, but ¬ (unknown) i

WHEN or THEN Key Constraints Suppose a table has two columns representing a period of time throughout which the information conveyed by the other columns is recorded as having

Advantages of Wrapping   The PL/SQL Wrapper convert the PL/SQL source code into a transitional form of the object code. By hiding the application internals, the Wrapper secure

Keyword and Parameter Description: table_reference: This specifies a table or view that should be accessible when you execute the DELETE statement, and for that you must

Organi c Evolution Evolution is a slow continuous, irreversible and natural process of change to give rise to advance and diverse forms of life i.e. formation of new specie

PITS Depressions in secondary cell wall is called pit. A pit present on the free cell wall surface without its partner is called Blind pit. It consists of 2 parts -