Using extend - collection method, PL-SQL Programming

Assignment Help:

Using EXTEND

To enlarge the size of a collection, use EXTEND. This process has 3 forms. The EXTEND appends one null element to a collection. And the EXTEND(n) appends n null elements to a collection. EXTEND(n,i) appends n copies of the ith element to the  collection. For e.g. the statement below appends 5 copies of element 1 to nested table courses:

courses.EXTEND(5,1);

You cannot use the EXTEND to initialize an automatically null collection. In addition if you impose the NOT NULL constraint on a TABLE or VARRAY type, you cannot apply the first two forms of EXTEND to collections of that kind.

The EXTEND operates on the internal size of the collection, that includes any deleted elements. Therefore, if EXTEND encounters deleted the elements, then it includes them in its tally. The PL/SQL keeps placeholders for the deleted elements so that you can swap them whenever you wish. Consider the example shown below:

DECLARE

TYPE CourseList IS TABLE OF VARCHAR2(10);

courses CourseList;

BEGIN

courses := CourseList('Biol 4412', 'Psyc 3112', 'Anth 3001');

courses.DELETE(3); -- delete element 3

/* PL/SQL keeps a placeholder for element 3. So, the

next statement appends element 4, not element 3. */

courses.EXTEND; -- append one null element

/* Now element 4 exists, so the next statement does

not raise SUBSCRIPT_BEYOND_COUNT. */

courses(4) := 'Engl 2005';

Whenever it includes deleted elements, then the internal size of a nested table differs from the values returned by the COUNT and LAST. For illustration, when you initialize a nested table with five elements, delete the elements 2 & 5, then the internal size is 5, and the COUNT returns 3, &  the LAST returns 4. All the deleted elements are treated similarly.


Related Discussions:- Using extend - collection method

Using operator ref - manipulating objects pl sql, Using Operator REF: ...

Using Operator REF: You can retrieve refs by using the operator REF that, like VALUE, takes as its argument a correlation variable. In the illustration below, you retrieve one

An active database in pl-sql, Consider the following set of database tables...

Consider the following set of database tables (same tables from Assignment 6-1). Please take note of foreign keys (most of them carry the same names as the corresponding primary ke

Merge two data sources to sql azure database, Project Description: I hav...

Project Description: I have two types of data sources. One that is a list in SharePoint and another that is an access desktop database. The access desktop database is fairly com

Controlling autonomous transactions, Controlling Autonomous Transactions ...

Controlling Autonomous Transactions The first SQL statement in an autonomous routine starts a transaction. Whenever one transaction ends, the next SQL statement starts the oth

Overloading method in pl/sql, Overloading: Similar to packaged subprog...

Overloading: Similar to packaged subprograms, methods of the same type can be overloaded. That is, you can use similar name for various methods if their formal parameters diff

Expression in assignment statement - pl sql, Expression: This is a ran...

Expression: This is a randomly complex combination of constants, variables, literals, operators, & function calls. The simplest expression consists of a single variable. If th

Example of foreign key constraint - sql, Example of Foreign Key Constraint ...

Example of Foreign Key Constraint Example: Alternative formulation for 6.3 as a foreign key constraint ALTER TABLE EXAM_MARK ADD CONSTRAINT Must_be_enrolled_to_take_exam

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

Deleting objects in pl sql, Deleting Objects You can use the DELETE st...

Deleting Objects You can use the DELETE statement to eradicate objects from an object table. To eradicate objects selectively, you use the WHERE clause, as shown below: BEG

Variables and constants in pl/sql, V ariables and Constants in PL/SQL ...

V ariables and Constants in PL/SQL The PL/SQL permits you to declare constants and variables, and then use them in SQL and procedural statements anywhere in the expression. Th

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