OCP-047 CREATE VIEW 必须指定列别名

最新推荐文章于 2024-06-08 09:42:14 发布

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最新推荐文章于 2024-06-08 09:42:14 发布

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分类专栏： OCP 文章标签： date join each

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本文介绍了在Oracle数据库中创建视图时遇到ora-00998错误的原因，强调了指定列别名的重要性。通过示例展示了使用JOIN操作查询ORDERS和ORDER_ITEMS表，并在GROUP BY子句中聚合数据，创建带有"NO OF ITEMS"别名的视图。

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考点：创建视图必须指定列别名 ,否则创建视图的时候会提示ora-00998 错误信息

18. View the Exhibit and examine the data 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 view successfully?
A. 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.

B. 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.

C. CREATE OR REPLACE VIEW ord_vu
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.
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

WITH CHECK OPTION.

Answer: B