66. View the Exhibit and examine the data in the COSTS table.
You need to generate a report that displays the IDs of all products in the COSTS table whose unit price is
at least 25% more than the unit cost. The details should be displayed in the descending order of 25% of
the unit cost.
You issue the following query:
SQL>SELECT prod_id
FROM costs
WHERE unit_price >= unit_cost * 1.25
ORDER BY unit_cost * 0.25 DESC;
Which statement is true regarding the above query?
A. It executes and produces the required result.
B. It produces an error because an expression cannot be used in the ORDER BY clause.
C. It produces an error because the DESC option cannot be used with an expression in the ORDER BY
clause.
D. It produces an error because the expression in the ORDER BY clause should also be specified in the
SELECT clause.
Answer: A
答案解析：
Order by可以只用表达式来排序
order by 可以表达式sal*10
可以列别名 sal10
可以双引号 "sal10"
sh@TESTDB> SELECT prod_id
2 FROM costs
3 WHERE unit_price >= unit_cost * 1.25
4 and rownum<6
5 ORDER BY unit_cost * 0.25 DESC;
PROD_ID
----------
14
14
14
14
13