80、View the exhibit and examine the structure in ORDERS and ORDER_ITEMS tables.

You need to create a view that displays the ORDER_ID, ORDER_DATE, and the total number of items in each order.

Which CREATE VIEW statement would create the views successfully?

A . AS SELECT o.order_id, o.order_date, COUNT (i.line_item_id)

FROM orders o JOIN order_items i

ON (o.order_id = i.order_id)

GROUP BY o.order_id, o.order_date;

 

B. CREATE OR REPLACE VIEW ord_vu (order_id, order_date)

AS SELECT o.order_id, o.order_date, COUNT (i.line_item_id)

"NO OF ITEMS"

FROM orders o JOIN order_items i ON

(o.order_id = i.order_id) GROUP BY o.order_id,

o.order_date;

 

C. CREATE OR REPLACE VIEW ord_vu

AS SELECT o.order_id, o.order_date, COUNT (i.line_item_id)

"NO OF ITEMS"

FROM orders o JOIN order_items i

ON (o.order_id = i.order_id) GROUP BY

o.order_id, o.order_date;

 

D. CREATE OR REPLACE VIEW ord_vu

AS SELECT o.order_id, o.order_date, COUNT (i.line_item_id) ||

"NO OF ITEMS"

FROM orders o JOIN order_items i

ON (o.order_id = i.order_id) GROUP BY

o.order_id, o.order_date

WHITH CHECK OPTION;

Correct Answer: C

Section: (none) Explanation：A答案会报错：ORA-00998: 必须使用列别名命名此表达式，缺少一个别名;B答案视图缺少一个列名，如果加上"NO OF ITEMS"就是正确的。