Manipulating individual elements - pl/sql, PL-SQL Programming

Assignment Help:

Manipulating Individual Elements

Faraway you have manipulated an entire collection. Within the SQL, to manipulate the individual elements of the collection, and then use the operator TABLE. The operand of TABLE is a subquery which returns a single column value for you to manipulate. That the value is the nested table or the varray.
In the illustration below, you add a row to the History Department nested table stored in the column courses:



BEGIN
INSERT INTO
TABLE(SELECT courses FROM department WHERE name = ’History’)
VALUES(3340, ’Modern China’, 4);
END;


In the next illustration, you revise the number of credits for two courses offered by the Psychology Department:

DECLARE
adjustment INTEGER DEFAULT 1;
BEGIN
UPDATE TABLE(SELECT courses FROM department
WHERE name = ’Psychology’)
SET credits = credits + adjustment
WHERE course_no IN (2200, 3540);
END;

In the following illustration, you retrieve the number and the title of a specific course offered by the History Department:

DECLARE
my_course_no NUMBER(4);
my_title VARCHAR2(35);
BEGIN
SELECT course_no, title INTO my_course_no, my_title
FROM TABLE(SELECT courses FROM department
WHERE name = ’History’)
WHERE course_no = 3105;
...
END;


In the next illustration, you delete all 5-credit courses offered by the English Department:

BEGIN
DELETE TABLE(SELECT courses FROM department
WHERE name = ’English’)
WHERE credits = 5;
END;



In the following illustration, you recover the title and cost of the Maintenance Department’s fourth project from the varray column projects:

DECLARE
my_cost NUMBER(7,2);
my_title VARCHAR2(35);
BEGIN
SELECT cost, title INTO my_cost, my_title
FROM TABLE(SELECT projects FROM department
WHERE dept_id = 50)
WHERE project_no = 4;
...
END;


Presently, you cannot reference the individual elements of a varray in an UPDATE, INSERT, or DELETE statement. And hence, you should use the PL/SQL procedural statements. In the illustration below, the stored procedure add_project inserts a new project into the department’s project list at a given position a shown:

CREATE PROCEDURE add_project (
dept_no IN NUMBER,
new_project IN Project,
position IN NUMBER) AS
my_projects ProjectList;
BEGIN

SELECT projects INTO my_projects FROM department
WHERE dept_no = dept_id FOR UPDATE OF projects;
my_projects.EXTEND; -- make room for new project
/* Move varray elements forward. */
FOR i IN REVERSE position..my_projects.LAST - 1 LOOP
my_projects(i + 1) := my_projects(i);
END LOOP;
my_projects(position) := new_project; -- add new project
UPDATE department SET projects = my_projects
WHERE dept_no = dept_id;
END add_project;

The stored procedure updates below for a given project is:

CREATE PROCEDURE update_project (
dept_no IN NUMBER,
proj_no IN NUMBER,
new_title IN VARCHAR2 DEFAULT NULL,
new_cost IN NUMBER DEFAULT NULL) AS
my_projects ProjectList;
BEGIN
SELECT projects INTO my_projects FROM department
WHERE dept_no = dept_id FOR UPDATE OF projects;
/* Find project, update it, then exit loop immediately. */
FOR i IN my_projects.FIRST..my_projects.LAST LOOP
IF my_projects(i).project_no = proj_no THEN
IF new_title IS NOT NULL THEN
my_projects(i).title := new_title;
END IF;
IF new_cost IS NOT NULL THEN
my_projects(i).cost := new_cost;
END IF;
EXIT;
END IF;
END LOOP;
UPDATE department SET projects = my_projects
WHERE dept_no = dept_id;
END update_project;


Related Discussions:- Manipulating individual elements - pl/sql

Appgen to sap data export, We are seeking a freelance consultant that is fa...

We are seeking a freelance consultant that is familiar with Appgen applications. We require exporting all our data into a format appropriate for importing into SAP Business One. Pl

Maintain an audit trail of product table changes, The accuracy of product t...

The accuracy of product table data is critical and the Brwebean's. owner wants to have an audit file that contains information regarding all DML activity on the BB_PRODUCT table. T

Exit statement - syntax, EXIT Statement   You can use the EXIT stateme...

EXIT Statement   You can use the EXIT statement to exit a loop. The EXIT statement has 2 forms: the conditional EXIT WHEN and the unconditional EXIT. With the either form, you

Initializing objects in pl sql, Initializing Objects: Till you initiali...

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 me

Pl/sql expressions , Pl/SQL Expressions The Expressions are constructed...

Pl/SQL Expressions The Expressions are constructed by using the operands and operators. An operand is a constant, literal, variable, or function call which contributes a value

Use triggers to maintain referential integrity, At times, Brewbean's has ch...

At times, Brewbean's has changed the id number for existing products. In the past, they have had to add a new product row with the new id to the BB_PRODUCT table, modify all the co

Data types in sql, Data Types in SQL SQL's concept does not differ sig...

Data Types in SQL SQL's concept does not differ significantly from that defined in the theory book, apart from that business concerning NULL. However, the theory book equates

Magento change address format depending on store, Magento change address fo...

Magento change address format depending on store Project Description: What I need is that depending on the store in which the customer bought the address should change the fo

Scope rules - user-defined exceptions, Scope Rules You cannot declare ...

Scope Rules You cannot declare an exception twice in the similar block. Though, you can, declare the similar exception in 2 different blocks. The Exceptions declared in a bloc

Parameter and keyword description - update statement, Parameter and Keyword...

Parameter and Keyword Description:   table_reference: This keyword identifies the table or view that should be accessible when you execute the UPDATE statement, and for wh

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