20.choose two
Examine the description of the EMP_DETAILS table given below:
Which two statements are true regarding SQL statements that can be executed on the EMP_DETAIL table?
A) You cannot add a new column to the table with LONG as the data type.
B) An EMP_IMAGE column can be included in the GROUP BY clause.
C) You can alter the table to include the NOT Nun., constraint on the EMP_IMAGE column.
D) An EMP_IMAGE column cannot be included in the ORDER BY clause.
Answer:AD
(解析：
答案 A：
SQL> alter table sales add emp_info long;
alter table sales add emp_info long *
第 1 行出现错误:
ORA-01754: 表只能包含一个 LONG 类型的列。
答案 D：
SQL> select * from sales
2 order by emp_image;
select * from sales
*
第 1 行出现错误:
ORA-00997: 非法使用 LONG 数据类型
）