LOOP statement runs one or more statements while a condition is
LOOP statement ends when the condition becomes
NULL, or when a statement inside the loop transfers control outside the loop or raises an exception.
Expression whose value is
boolean_expression is evaluated at the beginning of each iteration of the loop. If its value is
TRUE, the statements after
LOOP run. Otherwise, control transfers to the statement after the
To prevent an infinite loop, at least one statement must change the value of
NULL, transfer control outside the loop, or raise an exception. The statements that can transfer control outside the loop are:
Labels improve readability, especially when
LOOP statements are nested, but only if you ensure that the label in the
LOOP statement matches a label at the beginning of the same
LOOP statement (the compiler does not check).
Example 4-28, "WHILE LOOP Statements"