OCP-1Z0-051 第112题 GROUP BY,ORDER BY子句

一、原题

View the Exhibit and examine the structure of the PROMOTIONS table.



Evaluate the following SQL statement:

SQL> SELECT promo_category, AVG(promo_cost) Avg_Cost, AVG(promo_cost)*.25 Avg_Overhead

             FROM promotions

          WHERE UPPER(promo_category) IN ('TV', 'INTERNET','POST')

    GROUP BY Avg_Cost

    ORDER BY Avg_Overhead;

The above query generates an error on execution.

Which clause in the above SQL statement causes the error?

A. WHERE

B. SELECT
C. GROUP BY
D. ORDER BY

答案：C

二、题目翻译

看下面PROMOTIONS表的结构:

下面的SQL语句:

上面的查询会报错,

是哪一个子句引起的错误？

三、题目解析

GROUP BY后面不能使用列别名。