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。