OCP-1Z0-051 第90题 转换函数

一、原题

Examine the structure and data in the PRICE_LIST table:

name                           Null           Type

PROD_ID            NOT NULL      NUMBER(3)

PROD_PRICE                             VARCHAR2(10)

PROD_ID    PROD_PRICE

100         $234.55

101         $6,509.75

102         $1,234

You plan to give a discount of 25% on the product price and need to display the discount amount in the same format as the PROD_PRICE.

Which SQL statement would give the required result?

A. SELECT TO_CHAR(prod_price* .25,'$99,999.99')

        FROM PRICE_LIST;

B. SELECT TO_CHAR(TO_NUMBER(prod_price)* .25,'$99,999.00')

       FROM PRICE_LIST;
C. SELECT TO_CHAR(TO_NUMBER(prod_price,'$99,999.99')* .25,'$99,999.00')

       FROM PRICE_LIST;
D. SELECT TO_NUMBER(TO_NUMBER(prod_price,'$99,999.99')* .25,'$99,999.00')

        FROM PRICE_LIST;

答案：C

二、题目翻译

下面是查看 PRICE_LIST表的结构和数据

现在计划给product price打折25%，并使用与PROD_PRICE相同格式显示打折后的值

下面哪句SQL能给出所需的结果?

三、题目解析

因为PROD_PRICE是vachar2(10)类型，所以不能直接运算，需要先TO_NUMBER转换成数据型后才能进行计算，然后再TO_CHAR转换成字符型显示。