Iterative Control:
An Iterative statement is a set of statements which are performed a number of times depending on the value in the LOOP statement. There are three fundamental forms of LOOP statements which are given below:
LOOP
The easiest form of LOOP statement is the basic ( or infinite) loop, that encloses a sequence of statements among the keywords LOOP and END LOOP. The syntax is given below.
Syntax
LOOP Sequence_of_statements; End LOOP.
With every Iteration of the loop the sequence of statements is executed, the control resumes at the top of the loop. The given example describes the execution of the LOOP statement.
Example
DECLARE
a NUMBER:=10;
BEGIN
LOOP DBMS_OUTPUT.PUT_LINE(a);
END LOOP;
END;
The output leads to an error. Since the number of times the loop must be executed is not specified and it goes for an infinite loop. Sequentially to terminate the loop a few form of termination statement is needed. The EXIT statement is used to perform this operation.
Example
DECLARE
A NUMBER:=&A;
BEGIN
LOOP DBMS_OUTPUT.PUT_LINE(A);
a:=a+1;
IF a > 20 THEN
EXIT;
End if;
END LOOP;
END;
Till the value crosses 20 the loop is executed and once the value for the variable reaches to 20 the loop is terminated by using the EXIT statement. This EXIT statement can be additionally simplified through the usage of EXIT_WHEN statement.