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以往旧题索引：

http://www.itpub.net/forum.php?m ... eid&typeid=1808

原始出处：

http://www.plsqlchallenge.com/

作者：Steven Feuerstein

运行环境：SQLPLUS, SERVEROUTPUT已打开

注：本题给出答案时候要求给予简要说明才能得到奖品

我执行了这些语句:

CREATE TYPE plch_food_t AS OBJECT

(

name VARCHAR2 (100),

food_group VARCHAR2 (100),

grown_in VARCHAR2 (100)

)

NOT FINAL;

/

CREATE TYPE plch_dessert_t

UNDER plch_food_t

(

contains_chocolate CHAR (1),

year_created NUMBER (4)

)

NOT FINAL;

/

CREATE TYPE plch_cake_t

UNDER plch_dessert_t

(

diameter NUMBER,

inscription VARCHAR2 (200)

);

/

CREATE TABLE meals

(

served_on     DATE,

appetizer     plch_food_t,

main_course   plch_food_t,

dessert       plch_dessert_t

);

BEGIN

INSERT INTO meals

VALUES (SYSDATE + 1,

plch_food_t ('Shrimp cocktail', 'PROTEIN', 'Ocean'),

plch_food_t ('Stir fry tofu', 'PROTEIN', 'Vat'),

plch_cake_t ('Apple Pie',

'FRUIT',

'Baker''s Square',

'N',

2001,

8,

NULL));

INSERT INTO meals

VALUES (SYSDATE + 1,

plch_food_t ('Fried Calamari', 'PROTEIN', 'Ocean'),

plch_dessert_t ('Butter cookie',

'CARBOHYDRATE',

'Oven',

'N',

2001),

plch_cake_t ('French Silk Pie',

'CARBOHYDRATE',

'Baker''s Square',

'Y',

2001,

6,

'To My Favorite Frenchman'));

INSERT INTO meals

VALUES (SYSDATE + 1,

plch_food_t ('Fried Calamari', 'PROTEIN', 'Ocean'),

plch_cake_t ('French Silk Pie',

'CARBOHYDRATE',

'Baker''s Square',

'Y',

2001,

6,

'To My Favorite Frenchman'),

plch_dessert_t ('Butter cookie',

'CARBOHYDRATE',

'Oven',

'N',

2001));

END;

/

哪些选项在执行之后会导致下列两行被显示(两行的顺序无关紧要)？

Butter cookie-N

French Silk Pie-Y

(A)

BEGIN

FOR rec IN (SELECT *

FROM meals

WHERE TREAT (main_course AS plch_dessert_t) IS NOT NULL)

LOOP

DBMS_OUTPUT.put_line (

rec.main_course.name || '-' ||

rec.main_course.contains_chocolate);

END LOOP;

END;

/

(B)

DECLARE

l_dessert   plch_dessert_t;

BEGIN

FOR rec IN (SELECT * FROM meals)

LOOP

BEGIN

l_dessert := TREAT (rec.main_course AS plch_dessert_t);

DBMS_OUTPUT.put_line (

l_dessert.name || '-' || l_dessert.contains_chocolate);

EXCEPTION

WHEN VALUE_ERROR

THEN

NULL;

END;

END LOOP;

END;

/

(C)

BEGIN

FOR rec IN (SELECT * FROM meals)

LOOP

DBMS_OUTPUT.put_line (

CASE

WHEN rec.main_course.contains_chocolate IS NOT NULL

THEN

rec.main_course.name

|| '-'

|| rec.main_course.contains_chocolate

ELSE

NULL

END);

END LOOP;

END;

/

(D)

BEGIN

FOR rec IN (SELECT *

FROM meals

WHERE TREAT (main_course AS plch_dessert_t) IS NOT NULL)

LOOP

DBMS_OUTPUT.put_line (

rec.main_course.name || '-' ||

rec.TREAT (rec.main_course AS plch_dessert_t).contains_chocolate);

END LOOP;

END;

/

(E)

DECLARE

l_dessert   plch_dessert_t;

BEGIN

FOR rec IN (SELECT *

FROM meals

WHERE TREAT (main_course AS plch_dessert_t) IS NOT NULL)

LOOP

l_dessert := TREAT (rec.main_course AS plch_dessert_t);

DBMS_OUTPUT.put_line (

rec.main_course.name || '-' ||

l_dessert.contains_chocolate);

END LOOP;

END;

/