Less

5Writing Control Structures

Copyright © 2004, Oracle. All rights reserved.

Objectives

After completing this lesson, you should be able to do
the following:
• Identify the uses and typesof control structures
• Construct an IF statement
• Use CASE statements and CASE expressions
• Construct and identify different loop statements
• Make use of guidelines while using the conditionalcontrol structures

5-2

Copyright © 2004, Oracle. All rights reserved.

Controlling Flow of Execution

for
loop

while

5-3

Copyright © 2004, Oracle. All rights reserved.

IFStatements

Syntax:
IF condition THEN
statements;
[ELSIF condition THEN
statements;]
[ELSE
statements;]
END IF;

5-4

Copyright © 2004, Oracle. All rights reserved.

IF Statements

5-5Copyright © 2004, Oracle. All rights reserved.

Simple IF Statement

DECLARE
myage number:=31;
BEGIN
IF myage < 11
THEN
DBMS_OUTPUT.PUT_LINE(' I am a child ');
END IF;
END;
/

5-6Copyright © 2004, Oracle. All rights reserved.

IF THEN ELSE Statement

SET SERVEROUTPUT ON
DECLARE
myage number:=31;
BEGIN
IF myage < 11
THEN
DBMS_OUTPUT.PUT_LINE(' I am a child ');
ELSEDBMS_OUTPUT.PUT_LINE(' I am not a child ');
END IF;
END;
/

5-7

Copyright © 2004, Oracle. All rights reserved.

IF ELSIF ELSE Clause
DECLARE
myage number:=31;
BEGIN
IF myage < 11THEN
DBMS_OUTPUT.PUT_LINE(' I
ELSIF myage < 20
THEN
DBMS_OUTPUT.PUT_LINE(' I
ELSIF myage < 30
THEN
DBMS_OUTPUT.PUT_LINE(' I
ELSIF myage < 40
THEN
DBMS_OUTPUT.PUT_LINE(' I
ELSEDBMS_OUTPUT.PUT_LINE(' I am
END IF;
END;
/

5-8

am a child ');

am young ');

am in my twenties');

am in my thirties');
always young ');

Copyright © 2004, Oracle. All rights reserved.

NULLValues in IF Statements

DECLARE
myage number;
BEGIN
IF myage < 11
THEN
DBMS_OUTPUT.PUT_LINE(' I am a child ');
ELSE
DBMS_OUTPUT.PUT_LINE(' I am not a child ');
END IF;
END;
/

5-9...