Saturday, 11 August 2012

PL/SQL FOR and WHILE LOOP / Iterative Statements





Introduction to PL/SQL LOOP Statement

PL/SQL LOOP is an iterative control structure that allows you to execute a sequence of statements repeatedly.

    There are three types of PL/SQL loop Statements
  • Simple Loop

  • While Loop

  • For Loop


Type 1) Simple Loop
A Simple Loop is used when a set of statements is to be executed at least once before the loop terminates. An EXIT condition must be specified in the loop, otherwise the loop will get into an infinite number of iterations. When the EXIT condition is satisfied the process exits from the loop.

Syntax :

LOOP
statements;
EXIT;
{or EXIT WHEN condition;}
END LOOP;


Type 2) While Loop
A WHILE LOOP is used when a set of statements has to be executed as long as a condition is true. The condition is evaluated at the beginning of each iteration. The iteration continues until the condition becomes false.

Syntax :

WHILE
LOOP statements;
END LOOP;


3) FOR Loop
A FOR LOOP is used to execute a set of statements for a predetermined number of times. Iteration occurs between the start and end integer values given. The counter is always incremented by 1. The loop exits when the counter reachs the value of the end integer.

Syntax :

FOR counter IN value1..value2
LOOP statements;
END LOOP;


value1 - Start integer value.
value2 - End integer value.
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