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Tutorial 9 : Oracle 9i: PL/SQL Control Structures |
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This tutorial teaches about how to structure flow of control through a PL/SQL program. The control structures of PL/SQL are simple yet powerful. Control structures in PL/SQL can be divided into selection or conditional, iterative and sequential.
Control Structures
This chapter teaches about how to structure flow of control through a PL/SQL program. The control structures of PL/SQL are simple yet powerful. Control structures in PL/SQL can be divided into selection or conditional, iterative and sequential.
Conditional Control (Selection): This structure tests a condition, depending on the condition is true or false it decides the sequence of statements to be executed. Example
IF-THEN, CASE and searched CASE statements.
Syntax for IF-THEN
IF THEN
Statements
END IF;
Example:
IF-THEN-ELSE:
IF THEN
Statements
ELSE
statements
END IF;
Example:
IF-THEN-ELSIF:
IF THEN
Statements
ELSIF THEN
Statements
ELSE
Statements
END IF;
Iterative Control
LOOP statement executes the body statements multiple times. The statements are placed between LOOP – END LOOP keywords.
The simplest form of LOOP statement is an infinite loop. EXIT statement is used inside LOOP to terminate it.
Syntax for LOOP- END LOOP
LOOP
Statements
END LOOP;
Example:
BEGIN
LOOP
DBMS_OUTPUT.PUT_LINE (‘Hello’);
END LOOP;
END;
Labeling Loops
We can label Loops. A Label is undeclared identifier enclosed between double angle brackets( Ex. <>). The following example demonstrates usage of labels in loops.
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