This document provides an overview of PL/SQL including: - PL/SQL block structure with declare, execution, and exception sections - Variables, constants, datatypes - Control structures like IF/ELSE statements and loop structures - Procedures and functions - Uses of PL/SQL include combining SQL with procedural logic, writing reusable code, and handling exceptions.

1. PL/SQL

2. Overview..
 Introduction
 PL/SQL Block Structure
 PL/SQL Variables
 PL/SQL IF Statement
 PL/SQL Loop Statement:
 PL/SQL WHILE Loop Statement PL/SQL FOR Loop
Statement.
 PL/SQL Function ; PL/SQL Procedure
 Exceptions
 Cursors and Triggers

3. About SQL
 The purpose of SQL is to provide an interface to a
relational database such as Oracle Database,
and all SQL statements are instructions to the
database.
 The strengths of SQL provide benefits for all
types of users, including application
programmers, database administrators,
managers, and end users.

4. Why PL/SQL?
How can we have a chain of SQL statements which produce
result according to the output of previous queries?
How can we take any smart decisions based on users input
or based on output on previous queries..?
How can we automate any task using SQL?

5. Introduction
• The PL/SQL programming language was
developed by Oracle Corporation in the late
1980s as procedural extension language for
SQL and the Oracle relational database.
• PL/SQL, supplement SQL with standard
programming-language features like:
• Block (modular) structure
• Flow-control statements and loops
• Variables, constants, and types
• Structured data
• Customized error handling

6. Why PL/SQL?
• The purpose of PL/SQL is to combine database
language and procedural programming
language.
• By extending SQL, PL/SQL offers a unique
combination of power and ease of use.
• PL/SQL fully supports all SQL data manipulation
statements.
• We can write procedures and functions which
can be invoked from different applications.

7. PL/SQL Block
• PL/SQL is a block-structured language.
• Each program written in PL/SQL is written as a
block.
• Blocks can also be nested.
• Each block is meant for a particular task.

8. PL/SQL Block Structure
IS
BEGIN
EXCEPTION
END;
Header (named blocks only)
Declare Section
Execution Section
Exception Section

9. Header Section
Relevant for named blocks only
Stored procedures (used to perform repetitive code.)
Stored functions (used to return value to the calling block),
Packages (allows related objects to be stored together),
Triggers (pl/sql block executed implicitly whenever the
triggering event takes place).
Determines the way that the named block or program
must be called.
Includes the name, parameter list, and RETURN clause (for
a function only).

10. • Header Section: Example
• Below is header section of stored procedure:
CREATE OR REPLACE PROCEDURE
print ( p_num NUMBER ) …
• Below is header section of stored function:
CREATE OR REPLACE FUNCTION
add ( p_num1 NUMBER, p_num2 NUMBER )
RETURN NUMBER …

11. Declare Section
 Relevant for anonymous blocks.
 Contains declarations of variables, constants,
cursors, user-defined exceptions and types.
 Optional section , but if you have one, it must
come before the execution and exception sections.
DECLARE
v_name VARCHAR2(35);
v_id NUMBER := 0;

12. Execution Section
 Mandatory section of PLSQL block
 Contains SQL statements to manipulate data in the
database
 Contains PL/SQL statements to manipulate data in the
block.
 Every block must have at least one executable
statement in the execution section.
BEGIN
SELECT ename
INTO v_ename
FROM emp
WHERE empno = 7900 ;
DBMS_OUTPUT.PUT_LINE
(‘Employee name :’ || v_ename);
END;

13. Exception Section
 The last section of the PL/SQL block.
 It contains statements that are executed when a runtime
error occurs within a block.
 An optional section.
 Control is transferred to this section when an run time
error is encountered and it is handled
EXCEPTION
WHEN NO_DATA_FOUND THEN
DBMS_OUTPUT.PUT_LINE
(‘ There is no employee with Employee no 7900 ’);
END;

14. PL/SQL Variables
• These are placeholders that store the values that can change
through the PL/SQL Block
• PL/SQL lets you declare constants and variables, then use
them in SQL and procedural statements anywhere an
expression can be used
• A constant or variable must be declared before referencing it in
other statements

15. Syntax for declaring variables
variable_name [CONSTANT] datatype
[NOT NULL] [:= expr | DEFAULT expr]
Note: Square brace indicates optional
• Variable_name is the name of the variable.
• Datatype is a valid PL/SQL datatype.
• NOT NULL is an optional specification on the
variable.
• A value or DEFAULT value is also an optional
specification, where you can initialize a variable.
• Each variable declaration is a separate statement
and must be terminated by a semicolon.
• CONSTANT keyword is used to declare constants.

16. PL/SQL variables
• Valid variable declarations

 DECLARE
 v_Activedate DATE;
 V_cust_id NUMBER(2) NOT NULL := 10;
 V_Address VARCHAR2(13) := ’Pune’;
 V_sr_id NUMBER DEFAULT 201;
 V_Name VARCHAR2(20) DEFAULT ‘Aditya’
• Valid constant declaration

 c_constant CONSTANT NUMBER := 1400;
• Invalid Declarations
v_cust_id NUMBER(2) NOT NULL;
v_name VARCHAR2 DEFAULT ‘Sachin’;
c_constant CONSTANT NUMBER ;
c_constant NUMBER CONSTANT;

17. Guidelines for Declaring PL/SQL
Variables
• Follow the naming Rules
 The variable name must be less than 31 characters
 The starting of a variable must be an ASCII letter
 It can be either lowercase or uppercase
 A variable name can contain numbers, underscore, and dollar sign
characters followed by the first character
• Follow the naming conventions
• Initialize variables designated as NOT NULL and CONSTANT
• Declare one identifier per line
• Initialize identifiers by using the assignment operator (:=) or the
reserved word “DEFAULT”

18. Declaring variable of record type :
Example
DECLARE
-- Type declaration
TYPE EmpRec IS RECORD(
empno emp.empno%TYPE,
ename emp.ename%TYPE,
salary emp.sal%TYPE
);
-- Record type variable declaration
V_emp_Rec emprec;
V_emp_Rec
empno number(10)
ename varchar2(25)
salary varchar2(75)

19. Sample program of PL/SQL

20. Program using variables
DECLARE
X NUMBER(3) := 10;
Y NUMBER(3) := 20;
BEGIN
DBMS_OUTPUT.PUT_LINE
(‘The value of variable X is : ‘ || X);
DBMS_OUTPUT.PUT_LINE
(‘The value of variable Y is : ‘ || Y);
END;

21. Accepting variables from users
DECLARE
v_num1 NUMBER(3):=&n1;
v_num2 NUMBER(3):=&n2;
IS
BEGIN
DBMS_OUTPUT.PUT_LINE
(‘The value of variable v_num1 is : ‘ || v_num1);
DBMS_OUTPUT.PUT_LINE
(‘The value of variable v_num2 is : ‘ || v_num2);
END;

22. PL/SQL Control Structures
• PL/SQL, like other 3GL has a variety of control
structures which include
• Conditional statements
o IF
o CASE
• Loops
o Simple loop
o While loop
o For loop

23. IF .. End if
 Syntax
IF condition THEN
Statements;
ELSE
Statements;
END IF;

24. Simple example
-- Block to demonstrate IF...ELSE...END IF
DECLARE
v_empno emp.empno%TYPE;
v_comm emp.comm%TYPE;
BEGIN
SELECT comm INTO v_comm FROM emp
WHERE empno = v_empno;
IF v_comm IS NULL THEN
DBMS_OUTPUT.PUT_LINE
(‘This employee doesnt get commission');
ELSE
DBMS_OUTPUT.PUT_LINE
 (‘This employee gets commission’);
END IF;
DBMS_OUTPUT.PUT_LINE
('This line executes irrespective of the condition');
END;

25. PL/SQL Loop Control Structures
 LOOP Statements
• Simple Loops
• WHILE Loops
• FOR Loops

26. LOOP Statements
• Simple Loops
Note: Add EXIT statement to exit from the loop
• WHILE Loops
Note: Condition is evaluated before each iteration of the loop
LOOP
Sequence_of_statements;
END LOOP;
WHILE condition
LOOP
Statements;
END LOOP;

27. Loop Example
DECLARE
v_i NUMBER(2) := 1;
BEGIN
LOOP
DBMS_OUTPUT.PUT_LINE(‘Value : ‘|| v_i);
EXIT WHEN v_i = 10;
v_i:=v_i+1;
END LOOP;
END;

28. While loop example
DECLARE
v_i NUMBER(2) := 1;
BEGIN
WHILE ( v_i <= 10 )
LOOP
DBMS_OUTPUT.PUT_LINE(‘Value : ‘|| v_i);
v_i:=v_i+1;
END LOOP;
END;

29. For loop
• The number of iterations for simple loops and WHILE loops is not known in
advance, it depends on the loop condition. Numeric FOR loops, on the
other hand, have defined number of iterations.
 Where:
• counter: is an implicitly declared integer whose value
automatically increases or decreases by 1 on each iteration
• REVERSE: causes the counter to decrement from upper
bound to lower bound
• Low_bound: specifies the lower bound for the range of
counter values
• High_bound: specifies the upper bound for the range of
counter values
FOR counter IN [REVERSE] low_bound .. high_bound
LOOP
Statements;
END

30. For Loop example
BEGIN
FOR v_i IN 1..10
/* The LOOP VARIABLE v_i of
type BINARY_INTEGER is declared
automatically */
LOOP
DBMS_OUTPUT.PUT_LINE(‘Value : ‘|| v_i);
END LOOP;
END;

31. For Loop with EXIT condition
DECLARE
myNo NUMBER(5):= &myno;
counter NUMBER(5):=1;
BEGIN
FOR i IN 2..myNo-1
LOOP
counter:= counter+1;
EXIT WHEN myNo mod i = 0;
END LOOP;
IF counter = myNo-1 THEN
DBMS_OUTPUT.PUT_LINE( 'The given
number is prime' );
ELSE
DBMS_OUTPUT.PUT_LINE('The given number is
not
a prime number' );
END IF;
END;

32. Procedures
 A Procedure is a subprogram unit that consists of a group of
PL/SQL statements. Each procedure in Oracle has its own
unique name by which it can be referred. This subprogram unit is
stored as a database object. Below are the characteristics of this
subprogram unit.
 CREATE OR REPLACE PROCEDURE
 <procedure_name>
 (
 <parameterl IN/OUT <datatype>
 )
 [ IS | AS ]
 <declaration_part>
 BEGIN
 <execution part>
 EXCEPTION
 <exception handling part>
 END;

33. What is Function
 Functions is a standalone PL/SQL subprogram.
Like PL/SQL procedure, functions have a unique
name by which it can be referred. These are
stored as PL/SQL database objects. Below are
some of the characteristics of functions.
 CREATE OR REPLACE FUNCTION
<procedure_name>(<parameterl IN/OUT
<datatype>)RETURN <datatype>[ IS | AS
]<declaration_part>BEGIN<execution part>
EXCEPTION<exception handling part>END;

35. Add two numbers
declare
-- declare variable x, y
-- and z of datatype number
x number(5);
y number(5);
z number(7);
begin
-- Here we Assigning 10 into x
x:=10;
-- Assigning 20 into x
y:=20;
-- Assigning sum of x and y into z
z:=x+y;
-- Print the Result
dbms_output.put_line('Sum is '||z);
end;

36.  Swapping:
-- declare variable num1, num2
-- and temp of datatype number
num1 number;
num2 number;
temp number;
begin
num1:=1000;
num2:=2000;
-- print result before swapping
dbms_output.put_line('before');
dbms_output.put_line('num1 = '|| num1 ||' num2 = '|| num2);
-- swapping of numbers num1 and num2
temp := num1;
num1 := num2;
num2 := temp;
-- print result after swapping
dbms_output.put_line('after');
dbms_output.put_line('num1 = '|| num1 ||' num2 = '|| num2);
end;

37. Prime Number
declare
-- declare variable n, i
-- and temp of datatype number
n number;
i number;
temp number;
begin
-- Here we Assigning 13 into n
n := 13;
-- Assigning 2 to i
i := 2;
-- Assigning 1 to temp
temp := 1;

38. -- loop from i = 2 to n/2
for i in 2..n/2
loop
if mod(n, i) = 0
then
temp := 0;
exit;
end if;
end loop;
if temp = 1
then
dbms_output.put_line('true');
else
dbms_output.put_line('false');
end if;
end;
-- Program End

39. Fibonocci
declare
-- declare variable first = 0,
-- second = 1 and temp of datatype number
first number := 0;
second number := 1;
temp number;
n number := 5;
i number;
begin
dbms_output.put_line('Series:');
--print first two term first and second
dbms_output.put_line(first);
dbms_output.put_line(second);
-- loop i = 2 to n
for i in 2..n
loop
temp:=first+second;
first := second;
second := temp;
--print terms of fibonacci series
dbms_output.put_line(temp);
end loop;
end;
--Program End

40. Factorial
declare
-- it gives the final answer after computation
fac number :=1;
-- given number n
-- taking input from user
n number := &1;
-- start block
begin
-- start while loop
while n > 0 loop
-- multiple with n and decrease n's value
fac:=n*fac;
n:=n-1;
end loop;
-- end loop
-- print result of fac
dbms_output.put_line(fac);
-- end the begin block
end;

41. Max of two numbers:
1.ECLARE
2. N NUMBER;
3. M NUMBER;
4.BEGIN
5. DBMS_OUTPUT.PUT_LINE('ENTER A
NUMBER');
6. N:=&NUMBER;
7. DBMS_OUTPUT.PUT_LINE('ENTER A
NUMBER');
8. M:=&NUMBER;
9.IF N<M THEN
10. DBMS_OUTPUT.PUT_LINE(''|| N ||' IS
GREATER THAN '|| M ||'');
11.ELSE
12. DBMS_OUTPUT.PUT_LINE(''|| M ||' IS
GREATER THAN '|| N ||'');
13.END IF;
14.END;
15./

42. Sum of N natural numbers

43. Even or Odd
DECLARE
-- Declare variable n, s, r, len
-- and m of datatype number
n NUMBER := 1634;
r NUMBER;
BEGIN
-- Calculating modulo
r := MOD(n, 2);
IF r = 0 THEN
dbms_output.Put_line('Even');
ELSE
dbms_output.Put_line('Odd');
END IF;
END;
--End program

44. Leap year
-- To check if a
-- given year is leap year or not
DECLARE
year NUMBER := 1600;
BEGIN
-- true if the year is a multiple
-- of 4 and not multiple of 100.
-- OR year is multiple of 400.
IF MOD(year, 4)=0
AND
MOD(year, 100)!=0
OR
MOD(year, 400)=0 THEN
dbms_output.Put_line(year
|| ' is a leap year ');
ELSE
dbms_output.Put_line(year
|| ' is not a leap year.');
END IF;
END;