Disjunction - sql, PL-SQL Programming

Disjunction (OR, ∨)

Again we have nine rows instead of just four and again, when unknown is not involved, the rows are as for 2VL. Also, when anything is paired with true, the result is true, as in 2VL. Our intuition, that "p or q" is true exactly when at least one operand is true, is preserved.

526_Disjunction (OR, ∨).png

Figure: The SQL Truth Table for Disjunction

Now, in the theory book it is noted that disjunction could equally well be defined in terms of conjunction and negation, as

p ∨ q ≡ ¬ (¬ p ∧ ¬ q)

and the truth table in Figure is given as proof of that equivalence. The question arises, does the same equivalence hold in SQL? To answer that we need to look at the revised Figure.

1667_Disjunction 2.png

Figure: SQL Disjunction in Terms of SQL Negation and SQL Conjunction

Posted Date: 1/18/2013 4:12:59 AM | Location : United States







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

Write discussion on Disjunction - sql
Your posts are moderated
Related Questions
Problem: (a) Define the following terms: (i) data mining. (ii) OLAP. (b) Differentiate between snowflake schema and star schema. Support your answer with appropriate

Remote Operations: As the illustration shows below, the PL/SQL subprograms can execute the dynamic SQL statements which refer to the objects on a remote database: PROCEDURE

Package Specification The package specifications contain the public declarations. The scopes of these declarations are local to your database representation and global to the

Enrolment was split - SQL Example shows how relvars IS_CALLED and IS_ENROLLED_ON can be derived from the original ENROLMENT relvar, using projection in the initial assignment

(a) What are decision support systems, and what role do they play in the business environment? (b) Data warehousing is defined as "a subject-oriented, integrated, non-volatile c

Example of Table Literal - SQL Example: A Table Literal (correct version) VALUES ('S1', 'C1', 'Anne'), ('S1', 'C2', 'Anne'), ('S2', 'C1', 'Boris'), ('S3', 'C3'

Varrays versus Nested Tables The Nested tables are differing from varrays in the following ways: 1)  Varrays have a maximum size, while nested tables do not. 2)  Varrays are

Control Structures The Control structures are the most important PL/SQL extension to the SQL. Not only does PL/SQL let you manipulate Oracle data, it lets you process the data

Important Distinctions The list of important distinctions are given below: Value versus variable Syntax versus semantics Variable versus variable reference

Parameter and Keyword Description: package_name: This construct identifies the package. AUTHID Clause: This determine whether all the packaged subprograms impleme