While loop:
The while loop statement associate a condition with a sequence of statements enclosed by the keywords LOOP and END LOOP. Syntax of the WHILE LOOP is given below.
Syntax
While condition loop
Sequence_of_statements;
END LOOP;
The condition is evaluated before each iteration of the loop. If the condition becomes TRUE, the sequence of statements is executed and the control resumes at the top of the loop. If the condition becomes FALSE or NULL then the loop is bypassed and control passes to the next statement after end loop. The given example shows the total of the first 20 numbers by using the WHILE LOOP statement.
Example
DECLARE
X integer:=1;
Yinteger:=0;
BEGIN
WHILE x < = 20
LOOP Y:=Y+x; X:=X+1;
END LOOP;
DBMS_OUTPUT.PUT_LINE(Y);
END;
In the given example, the loop is executed only when the while condition is fulfilled.