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047-138

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-19 10:07:03 0 删除 编辑
138. View the Exhibit and examine the structure of the ORDER_ITEMS table.
Examine the following SQL statement:
SELECT order_id, product_id, unit_price
FROM order_items WHERE unit_price = (SELECT MAX(unit_price)
FROM order_items GROUP BY order_id).
You want to display the PRODUCT_ID of the product that has the highest
UNIT_PRICE per ORDER_ID.
What correction should be made in the above SQL statement to achieve this?
A. Replace = with the IN operator.
B. Replace = with the >ANY operator.
C. Replace = with the >ALL operator.
D. Remove the GROUP BY clause from the subquery and place it in the main query.
Answer: A
SELECT MAX(unit_price) FROM order_items GROUP BY order_id 会按order_id
返回多条记录
需试验

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