Initializing Objects:

Till you initialize an object by calling the constructor for its object type, the object is automatically null. That is, the object itself is null, not merely its attributes. Consider the

Illustration which is as shown:

DECLARE

r Rational; -- r become atomically null

BEGIN

r := Rational(2,3); -- r becomes 2/3

The null object is never equal to the other object. However, comparing a null object with any other object always results NULL. Also, if you assign an atomically null object to the other object, the other object becomes atomically null. Similarly, if you assign the non-value NULL to an object, the object becomes automatically null, as the illustration below shows:

DECLARE

r Rational;

BEGIN

r Rational := Rational(1,2); -- r becomes 1/2

r := NULL; -- r becomes atomically null

IF r IS NULL THEN ... -- condition yields TRUE

 

A good quality programming practice is to initialize an object in its declaration, as shown in the illustration shown below:

 

DECLARE

r Rational := Rational(2,3); -- r becomes 2/3

Posted Date: 10/6/2012 8:13:14 AM | Location : United States

Ask an Expert

Related Discussions:- Initializing objects in pl sql, Assignment Help, Ask Question on Initializing objects in pl sql, Get Answer, Expert's Help, Initializing objects in pl sql Discussions

Write discussion on Initializing objects in pl sql
Your posts are moderated

Write your message here..

Related Questions

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

Assigning and comparing collections, Assigning and Comparing Collections ... 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

Delete statement - syntax, DELETE Statement The DELETE statement elimin... DELETE Statement The DELETE statement eliminates whole rows of data from the specified table or view. Syntax:

Sql queries, SELECT a.child_fname,a.child_lname,concat(b.parent_title,b.par... SELECT a.child_fname,a.child_lname,concat(b.parent_title,b.parent_fname), b.parent_lname,b.parent_tphone FROM child a,parent b WHERE a.parent_id=b.parent_id ORDER BY a.child_fnam

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

Example of check constraints - sql, Example of Check Constraints Examp... Example of Check Constraints Example: Workaround for when subqueries not permitted in CHECK constraints CREATE FUNCTION NO_MORE_THAN_20000_ENROLMENTS ( ) RETURNS BOOLEAN

Passing cursor parameters, Passing Cursor Parameters You use the OPEN ... Passing Cursor Parameters You use the OPEN statement to pass the parameters to a cursor. Unless you want to accept the default values, each proper parameter in the cursor decl

Unnest operator in sql, UNNEST operator in SQL The inverse operator of... UNNEST operator in SQL The inverse operator of GROUP is UNGROUP. SQL has an operator, UNNEST, that can be used for similar purposes, but its method of invocation is somewhat p

Subprograms, Subprograms The PL/SQL has two types of subprograms known ... Subprograms The PL/SQL has two types of subprograms known as the procedures and functions that can take parameters and be invoked. As the following example represents, a subp

Advantages of subprograms, Advantages of Subprograms The Subprograms g... Advantages of Subprograms The Subprograms give extensibility; that is, tailor the PL/SQL language to suit your requirements. For illustration, if you require a procedure which