OCP-1Z0-051-V9.02-96题

96. Examine the structure of the INVOICE table.

name Null Type

INV_NO NOT NULL NUMBER(3)

INV_DATE DATE

INV_AMT NUMBER(10,2)

Which two SQL statements would execute successfully? (Choose two.)

A. SELECT inv_no,NVL2(inv_date,'Pending','Incomplete')

FROM invoice;

B. SELECT inv_no,NVL2(inv_amt,inv_date,'Not Available')

FROM invoice;

C. SELECT inv_no,NVL2(inv_date,sysdate-inv_date,sysdate)

FROM invoice;

D. SELECT inv_no,NVL2(inv_amt,inv_amt*.25,'Not Available')

FROM invoice;

Answer: AC

答案解析：

此题考NVL2参数类型是否一致的问题。

NVL2参考：/article/1348608.html

搭建环境：
创建表，并插入数据

sys@TEST0910> create table invoice
2 (inv_no number(3) not null,
3 inv_date date,
4 inv_amt number(10,2));

Table created.



sys@TEST0910> insert into invoice values(1,sysdate-2,100.2);

1 row created.

sys@TEST0910> select * from invoice;

INV_NO INV_DATE INV_AMT
---------- --------- ----------
1 16-SEP-13 100.2


A答案：

sys@TEST0910> SELECT inv_no,NVL2(inv_date,'Pending','Incomplete') FROM invoice;


INV_NO NVL2(INV_D
---------- ----------
1 Pending


inv_date非空，则返回Pending。且'Pending','Incomplete'数据类型一致，故正确。

B答案：

sys@TEST0910> SELECT inv_no,NVL2(inv_amt,inv_date,'Not Available') FROM invoice;
SELECT inv_no,NVL2(inv_amt,inv_date,'Not Available') FROM invoice
*
ERROR at line 1:
ORA-01858: a non-numeric character was found where a numeric was expected


sys@TEST0910> SELECT inv_no,NVL2(inv_amt,to_char(inv_date),'Not Available') FROM invoice;

INV_NO NVL2(INV_AMT,TO_CH
---------- ------------------
1 16-SEP-13

inv_amt非空，则返回inv_date，但要保证inv_date和'Not Available'数据类型一致，故用to_char显示转换。


C答案：
sys@TEST0910> SELECT inv_no,NVL2(inv_date,sysdate-inv_date,sysdate) FROM invoice;

INV_NO NVL2(INV_DATE,SYSDATE-INV_DATE,SYSDATE)
---------- ---------------------------------------
1 2.00181713

sysdate可以隐式转为数字类型。故正确。


D答案：
sys@TEST0910> SELECT inv_no,NVL2(inv_amt,inv_amt*.25,'Not Available')
2 FROM invoice;
SELECT inv_no,NVL2(inv_amt,inv_amt*.25,'Not Available')
*
ERROR at line 1:
ORA-01722: invalid number


sys@TEST0910> SELECT inv_no,NVL2(inv_amt,to_char(inv_amt*.25),'Not Available') FROM invoice;

INV_NO NVL2(INV_AMT,TO_CHAR(INV_AMT*.25),'NOT***
---------- ----------------------------------------
1 25.05

inv_amt非空，则返回inv_amt*.25，但要保证inv_amt*.25和'Not Available'数据类型一致，故用to_char显示转换。