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【071题库】最新OCP-071考试题库解析-第10题

【071题库】最新OCP-071考试题库解析-第10题

071考试是OCP考试科目的一种,由于071考题多变,我们专门收集整理了最新的考试题库,并对这些考题进行讲解,希望可以帮助广大考生。

每周五晚8点,我们有免费的OCP解析公开课,地址:https://ke.qq.com/course/326223  OCP题库交流群:1015267481,验证ocp

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071题库-第10题、choose the best answer

Evaluate the following SQL statement:

SQL> SELECT promo_id, promo_category

FROM promotions

WHERE promo_category = 'Internet' ORDER BY 2 DESC

UNION

SELECT promo_id, promo_category

FROM promotions

WHERE promo_category = 'TV'

UNION

SELECT promo_id, promo_category

FROM promotions

WHERE promo_category ='Radio';

Which statement is true regarding the outcome of the above query?

A) It produces an error because the ORDER BY clause should appear only at the end of a compound query-that is, with the last SELECT statement.

B) It executes successfully and displays rows in the descending order of PROMO_CATEGORY.

C) It produces an error because positional notation cannot be used in the ORDER BY clause with SET operators.

D) It executes successfully but ignores the ORDER BY clause because it is not located at the end of the compound statement.

Answer:A

(执行时 order by 子句只能出现最后的 select 语句,否则出现“ORA-00933: SQL 命令未正确结束”错误)

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