QUESTION NO: 10
Evaluate the following SQL statement:
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 executes successfully but ignores the ORDER BY clause because it is not located at the end
of the compound statement
D. It produces an error because positional notation cannot be used in the ORDER BY clause with
SET operators
Answer: A
答案解析：
参考：155：http://blog.csdn.net/rlhua/article/details/12014361
Explanation:
Using the ORDER BY Clause in Set Operations
The ORDER BY clause can appear only once at the end of the compound query.
Component queries cannot have individual ORDER BY clauses.
The ORDER BY clause recognizes only the columns of the first SELECT query.
By default, the first column of the first SELECT query is used to sort the output in an ascending order.