一、原題
See the structure of the PROGRAMS table:
![](https://img.laitimes.com/img/_0nNw4CM6IyYiwiM6ICdiwiIyVGduV2QvwVe0lmdhJ3ZvwFM38CXlZHbvN3cpR2Lc1TPB10QGtWUCpEMJ9CXsxWam9CXwADNvwVZ6l2c052bm9CXUJDT1wkNhVzLcRnbvZ2LcRTQE1UerhkYzlzRhZXUYpVd1kmYr50MZV3YyI2cKJDT29GRjBjUIF2LcRHelR3LcJzLctmch1mclRXY39DMzMTNyUzM0EzMwQDM1EDMy8CX0Vmbu4GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.jpg)
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、題目解析
關于NVL的用法,詳見
http://blog.csdn.net/holly2008/article/details/25251513