QUESTION NO: 7
Evaluate these two SQL statements:
SELECT last_name, salary, hire_date FROM EMPLOYEES ORDER BY salary DESC;
SELECT last_name, salary, hire_date FROM EMPLOYEES ORDER BY 2 DESC;
What is true about them?
A. The two statements produce identical results.
B. The second statement returns a syntax error.
C. There is no need to specify DESC because the results are sorted in descending order by default.
D. The two statements can be made to produce identical results by adding a column alias for the salary column in the second SQL statement.
Answer: A
答案解析：
order by 2意思是select语句中第二个排序，即为salary，即排序是一样的。
Explanation: Explanation: the two statement produce identical results as ORDER BY 2 will take the second column as sorting column.
Incorrect answer:
B there is no syntax error
Cresult are sorted in ascending order by default
DORDER BY 2 will take the second column as sorting column.