BEGIN

    FOR i IN 1..3 LOOP

        IF i < 3 THEN

            DBMS_OUTPUT.PUT_LINE (TO_CHAR(i));

        ELSE

            --试图改变下标的值，无效操作

            i := 2;

        END IF;

    END LOOP;

END;

BEGIN

    FOR i IN 1..3 LOOP

        DBMS_OUTPUT.PUT_LINE ('循环之中, i = ' || TO_CHAR(i));

    END LOOP;

    DBMS_OUTPUT.PUT_LINE ('循环之外, i = ' || TO_CHAR(i));

END;

DECLARE

    i NUMBER := 5;

BEGIN

    FOR i IN 1..3 LOOP

        --局部的i隐藏了全局的i

        DBMS_OUTPUT.PUT_LINE ('循环之中, i = ' || TO_CHAR(i));

    END LOOP;

    DBMS_OUTPUT.PUT_LINE ('循环之外, i = ' || TO_CHAR(i));

END;

<<main>>

DECLARE

    i NUMBER := 5;

BEGIN

    FOR i IN 1..3 LOOP

        DBMS_OUTPUT.PUT_LINE (

            '局部: ' || TO_CHAR(i) || ', 全局: ' ||

        TO_CHAR(main.i)  --使用标签限定引用全局的i

        );

    END LOOP;

END main;

BEGIN

    <<outer_loop>>

    FOR i IN 1..3 LOOP

        <<inner_loop>>

        FOR i IN 1..3 LOOP

            IF outer_loop.i = 2 THEN

                DBMS_OUTPUT.PUT_LINE

                    ('外部: ' || TO_CHAR(outer_loop.i) || ' 内部: '

                    || TO_CHAR(inner_loop.i));

            END IF;

        END LOOP inner_loop;

    END LOOP outer_loop;

END;