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.

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.

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

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

Ask an Expert

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

Write your message here..

Related Questions

Creating and destroying base tables, Creating and Destroying Base Tables: ... Creating and Destroying Base Tables: Example shows an SQL command to create the base table counterpart of the ENROLMENT variable Example  Creating a base table. CREATE T

Calculate the total shopper spending, Many of the reports generated from th... Many of the reports generated from the system calculate the total dollars in purchases for a shopper. Complete the following steps to create a function named TOT_PURCH_SF that acce

Theory of panspermia - origin of life, THEO R Y OF PANSPERMIA - Arrh... THEO R Y OF PANSPERMIA - Arrhenius (1908) postulated the cosmic panspermia theory that claims that organisms existed throughout the universe, and their spores, etc., could

Tables within a table - sql, Tables within a Table - SQL Figure here ... Tables within a Table - SQL Figure here is an exact copy of the one in the theory book and as before it is just an alternative way of representing some of the information con

Sql operators, SQL Operators The PL/SQL uses all the SQL set, compariso... SQL Operators The PL/SQL uses all the SQL set, comparison, and row operators in the SQL statements. This part briefly describes some of these operators.  1. Comparison Opera

Fetch statement - syntax, FETCH Statement The FETCH statement retrieve ... FETCH Statement The FETCH statement retrieve rows of data one at a time from the result set of the multi-row query. The data is stored in fields or variables which correspond t

Cursor variables in pl sql, Cursor Variables:   To execute the multi-... Cursor Variables:   To execute the multi-row query, the Oracle opens an unnamed work region that stores the processing information. You can use an explicit cursor that names

Mutual recursion, Mutual Recursion The Subprograms are mutually recursi... Mutual Recursion The Subprograms are mutually recursive if they directly or indirectly call each other. In the illustration below, the Boolean functions odd & even, that dete

Named notation, Named Notation The second procedure call uses the name... Named Notation The second procedure call uses the named notation. An arrow (=>) serve as the relationship operator that associates the formal parameter to the left of the arro

Advantages of exceptions, Advantages of Exceptions Using the exception... Advantages of Exceptions Using the exceptions for the error handling has many benefits. Without an exception handling, every time you issue a command, you should ensure for th