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

112.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
解析：列别名，不能用于where中，group by中，这其实是一个sql语句执行顺序的问题
1.from
2.where
3.group by
4.having
5.select
6.order by子句
通过这个可以知道order by 可以使用列别名