OCP-1Z0-051 补充题库 第41题 nvl函数的使用

一、原题

See the structure of the PROGRAMS table:

Which two SQL statements would execute successfully? (Choose two.)
    A. SELECT NVL(ADD_MONTHS(END_DATE,1),SYSDATE)
        FROM programs;
    B. SELECT TO_DATE(NVL(SYSDATE-END_DATE,SYSDATE))
        FROM programs;
    C. SELECT NVL(MONTHS_BETWEEN(start_date,end_date),'Ongoing')
         FROM programs;
    D. SELECT NVL(TO_CHAR(MONTHS_BETWEEN(start_date,end_date)),'Ongoing')
         FROM programs;

答案: A,D

二、题目解析

关于NVL的用法,详见
    http://blog.csdn.net/holly2008/article/details/25251513