Database management system chapter5

DATABASE MANAGEMENT SYSTEM
ORACLE SQL AND PL/SQL
PART II : Application Using Oracle PL/SQL
Teaching Aid Material
(www.phindia.com/gupta)

Authors invite your valuable feedback and suggestions on the book
pkdasgupta@gmail.com
RadhaKrishna_P@infosys.com

PART II : Application Using Oracle PL/SQL

CHAPTER 5
Introduction to PL/SQL Programming

CHAPTER 5
1 of 9

Why PL/SQL?


Better Performance



Higher Productivity



Full Portability



Tight Integration with SQL



Security

Page reference in the book: 147-152

CHAPTER 5
2 of 9

Character Set

Type

Characters

Uppercase, lowercase

A-Z , a-z

Digits

0-9

Mathematical and
punctuation symbols

~ ! @ # % & * ( )_ - + = | [ ] { }: ; ’’ ’ < > ?
/

White space

Space, tab, carriage return


CHAPTER 5
3 of 9

PL/SQL Identifiers






Identifiers are used to name PL/SQL objects such as constants,
variables, exceptions, procedures, cursors and reserved words.
Identifiers can be up to 30 characters in length, must start with a
letter and can include dollar sign, an underscore, and a pound sign.
Identifiers are case sensitive and cannot include space, tab or
carriage return. An identifier can be enclosed within double quotes.


CHAPTER 5
4 of 9

PL/SQL Literals


Literals are specific values and are not represented by identifiers



Can be character, number or Boolean value



To embed single quotes within a string literal, two single quotes next
to each other may be placed


CHAPTER 5
5 of 9

PL/SQL Delimiters


Delimiters are symbols with special meaning to PL/SQL



Used to separate identifiers from each other

Delimiter

Characteristics

--

Single-line comment indicator

/*

*/

Multiline comment delimiter

||

Concatenation operator

..

Range operator

;

Statement terminator


CHAPTER 5
6 of 9

PL/SQL Variable
Type
Scalar

Purpose
Numeric

NUMBER(p, s)
The maximum precision is 38 digits

Character

VARCHAR2, CHAR, LONG
CHAR and VARCHAR2 are up to 32767 bytes

Date

Range is between 01-Jan-4712BC and
31-Dec-9999AD

Boolean

Can hold TRUE, FLASE or NULL only

RAW

Similar to CHAR variables
LONG RAW is similar to LONG
LONG RAW can be up to 2 gigabytes


CHAPTER 5
7 of 9

PL/SQL Variable
Type
LOB

Purpose
BFILE

File locaters pointing to read only large objects in
operating system files

BLOB

BLOB locaters that point to large binary objects inside
the database

CLOB

CLOB locaters point to large character objects inside
the database

NCLOB

NCLOB locaters point large national character set
objects inside the database


CHAPTER 5
8 of 9

NULL




Represents unknown values as NULL values
NULL is never equal to anything
NVL, IS NULL or IS NOT NULL

CONSTANT



Requires an initial value
Value cannot be changed


CHAPTER 5
9 of 9

Default Value


A variable is assigned a default value of NULL while declaration



Can be initialized by assignment operator (: =)


CHAPTER 5
PL/SQL Structure
1 of 3

PL/SQL Structure
Declare
Variables, Cursors, Constants
Begin
PL/SQL statements
Exception
Statements for error handling
End;


CHAPTER 5
PL/SQL Structure
2 of 3

IF Statement


Allows actions based upon conditions



IF statement can also be nested



Three forms of IF statements:
IF … THEN …
IF … THEN … ELSE …
IF … THEN … ELSIF … ELSE ….


CHAPTER 5
PL/SQL Structure
3 of 3

Loops in PL/SQL


Simple Loop

Loop
PL/SQL statements
Exit Condition
End Loop



For Loop

For variable IN Start..End
PL/SQL Statements
End Loop;



While Loop

While <Condition> Loop
PL/SQL Statements
End Loop


CHAPTER 5
PL/SQL and Oracle
1 of 10

Scope of a Variable in Nested Block
PL/SQL statements can be nested

SQL Cursor




A cursor is a private SQL work area where all commands
defined in the cursor are executed
There are two types of cursors:


Implicit cursor



Explicit cursor


CHAPTER 5
PL/SQL and Oracle
2 of 10

Implicit Cursor


It is automatically created and handled by Oracle Server



Support all types of DMLs [Insert/Update/Delete]



Supports SELECT statement that returns only

Explicit Cursor


Needs to be declared explicitly by the programmer



It is handled using cursor-related commands


CHAPTER 5
PL/SQL and Oracle
3 of 10

INTO Clause





Into clause is mandatory in a PL/SQL program
It is placed between SELECT and FROM clauses
Acts as a container with the associated variable
Query must return only one row

%TYPE Attribute


Used to declare variables that refer to the column

% ROWTYPE Attribute


Represents a row in a table


CHAPTER 5
PL/SQL and Oracle
4 of 10

Example EX5_1


CHAPTER 5
PL/SQL and Oracle
5 of 10

EX5_2


CHAPTER 5
PL/SQL and Oracle
6 of 10

EX5_3


CHAPTER 5
PL/SQL and Oracle
EX5_5


7 of 10

CHAPTER 5
PL/SQL and Oracle
8 of 10

EX5_10


CHAPTER 5
PL/SQL and Oracle
EX5_11


9 of 10

CHAPTER 5
PL/SQL and Oracle
10 of 10

EX5_12


CHAPTER 5
Short/ Objective Type Question
Q1. Define identifiers, literals and delimiters in Oracle PL/SQL.
Q2. Explain %TYPE and %ROWTYPE attributes with the help of suitable examples.
Q3. What do you understand by SQL cursors?
Q4. Write a PL/SQL program which will accept three numbers and print the smallest among them.
SQL>@ C:/TTP/Q4
Enter value for a: 12
Enter value for b: 34
Enter value for c: 12
Smallest Number is 12
Q5. Write PL/SQL program using Loop … End Loop, For Loop and While Loop, which will accept integer from
1 to 10 and print factorial. For example, factorial of 5 is 5*4*3*2*1=120.
SQL>@ C:/TTP/Q5
Enter value for i_num: 6
FACTORIAL OF 6 IS 720

CHAPTER 5
Short/Objective Type Question
Q6. Write a PL/SQL program which will accept a number from 1 to 20 and display following the the figure.
SQL>@ C:/TTP/Q8
Enter value for i_num: 10
-- *
---- *
------ *
-------- *
---------- *
------------ *
-------------- *
---------------- *
------------------ *
-------------------- *

Q7.
(a)
(b)
(c)
(d)

The basic programming unit of a PL/SQL code is a
Procedure
Subprogram
Module
Block

Q8.
(a)
(b)
(c)
(d)

Which of the following sections of a PL/SQL program are optional?
Declarative Section
Exception Handler Section
Executable Section
All of these

CHAPTER 5
Home Assignment
WORKOUT

PART II : Application using Oracle PL/SQL
Periods Proposed – 18
Chapter 5

1 Period [Theory]
1 Period [Practical]

Chapter 6
Oracle Function, Procedure And Package

1 Period [Theory]

Chapter 7
Oracle Exception Handler and Database Triggers

1 Period [Theory]

Chapter 8
Implicit and Explicit Cursors

1 Period [Theory]
2 Periods [Practical]

Chapter 9
Advance Cursors

1 Period [Theory]

Chapter 10
PL/SQL Collection

1 Period [Theory]

Chapter 11
Oracle Objects and Dynamic SQL

1 Period [Theory]

Chapter 12
Performance Tuning

2 Period [Theory]

THE BOOK
The book is organized into three parts to introduce the
theoretical and programming concepts of DBMS. Part I
(Basic Concepts and Oracle SQL) deals with DBMS basic,
software analysis and design, data flow diagram, ER model,
relational algebra, normal forms, SQL queries, functions,
sub‐queries, different types of joins, DCL, DDL, DML, object
constraints and security in Oracle. Part II (Application Using
Oracle PL/SQL) explains PL/SQL basics, functions,
procedures, packages, exception handling, triggers, implicit,
explicit and advanced cursors using suitable examples. This
part also covers advanced concepts related to PL/SQL, such
as collection, records, objects, dynamic SQL and
performance tuning. Part III (Advanced Concepts and
Technologies) elaborates on advanced database concepts
such as query processing, file organization, distributed
architecture, backup, recovery, data warehousing, online
analytical processing and data mining concepts and their
techniques.

KEY FEATURES
 Includes about 300 examples to illustrate the concepts.
 Offers about 400 objective type questions.
 Provides about 100 challenging workouts.

TEACHING AID MATERIAL
Teaching Aid Material for all the chapters is provided on the
website of PHI Learning. Visit www.phindia.com/gupta to
explore the contents.

Visit PHI Learning Center www.phindia.com/gupta and Click on Instructor Resources to
access Teaching Aid Material for all the 18 chapters of the book.

Database management system chapter5

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