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047-203

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-19 10:54:41 0 删除 编辑
203. View the Exhibit button and examine the structures of ORDERS and
ORDER_ITEMS tables.In the ORDERS table, ORDER_ID is the PRIMARY KEY and in
the ORDER_ITEMS table, ORDER_ID and LINE_ITEM_ID form. the composite primary
key.Which view can have all the DML operations performed on it?
A. CREATE VIEW V1 AS SELECT order_id, product_id
FROM order_items;
B. CREATE VIEW V4(or_no, or_date, cust_id) AS SELECT order_id, order_date,
customer_id FROM orders WHERE order_date < '30mar2007' WITH CHECK OPTION;
C. CREATE VIEW V3 AS SELECT o.order_id, o.customer_id, i.product_id
FROM orders o, order_items I WHERE o.order_id=i.order_id;
D. CREATE VIEW V2 AS SELECT order_id, line_item_id, unit_price*quantity
total FROM order_items;
Answer: B
Performed:执行
不明白

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