Short-circuit evaluation-pl/sql expressions , PL-SQL Programming

Assignment Help:

Short-Circuit Evaluation

When computing a logical expression, the PL/SQL uses short-circuit evaluation. That is, the PL/SQL stops computing the expression as soon as the result can be determined. This permits you to write the expressions that might otherwise cause an error. Now consider the following OR expression:


DECLARE
...
on_hand INTEGER;
on_order INTEGER;
BEGIN
..
IF (on_hand = 0) OR ((on_order / on_hand) < 5) THEN
...
END IF;
END;


Whenever the value of on_hand is zero, the left operand yields TRUE, so the PL/SQL require not compute the right operand. If PL/SQL were to compute both operands before applying the OR operator, the right operand would cause a division by the zero error. In any case, it is a poor programming practice to rely on the short-circuit computation.


Related Discussions:- Short-circuit evaluation-pl/sql expressions

Processing transactions, Processing Transactions This part describes ho...

Processing Transactions This part describes how to do the transaction processing. You learn the fundamental techniques that safeguard the consistency of your database, involvin

Truth tables , Truth Tables: However in propositional logic - here we ...

Truth Tables: However in propositional logic - here we are restricted to expressing sentences and where the propositions are true or false - so we can check where a particular

Table represents an extension - sql, Table Represents an Extension - SQL ...

Table Represents an Extension - SQL It describes how each tuple in a relation represents a true instantiation of some predicate and each true instantiation is represented by s

Collections in pl sql, Collections:   The collection is an ordered gr...

Collections:   The collection is an ordered group of elements, all of similar type (for illustration, the grades for a class of students). Each element has an exclusive subsc

Iterative control: loop statement, Iterative Control: LOOP  Statements T...

Iterative Control: LOOP  Statements The LOOP statement executes a series of statements multiple times. There are 3 forms of LOOP statements: LOOP, WHILE-LOOP, & FOR-LOOP. LOOP

Package standard in pl/sql, Package STANDARD package named STANDARD d...

Package STANDARD package named STANDARD defines the PL/SQL atmosphere. The package specification globally declares the exceptions, types, and subprograms that are available a

Iterative control:exit statements, EXIT The EXIT statement forces a loop...

EXIT The EXIT statement forces a loop to done unconditionally. Whenever an EXIT statement is encountered, the loop is done immediately and controls the passes to the next statem

Overriding default locking, Overriding Default Locking By default, the...

Overriding Default Locking By default, the Oracle locks the data structures for you automatically. Though, you can request exact data locks on rows or tables when it is to you

Set operators - sql operators, Set Operators The Set operators combine...

Set Operators The Set operators combine the results of the two queries into one result. The INTERSECT returns all the distinct rows selected by both queries. The MINUS returns

Effects of null in table literal, Effects of NULL in Table Literal Whe...

Effects of NULL in Table Literal When a VALUES expression appears as the source value for an SQL INSERT statement, the key word NULL can appear as a field value, such that for

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd