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047-004

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-16 15:50:24 0 删除 编辑
4. View the Exhibit and examine the structure of the EMP table which is not
partitioned and not an indexorganized table.
Evaluate the following SQL statement:
ALTER TABLE emp DROP COLUMN first_name.
Which two statements are true regarding the above command? (Choose two.)
A. The FIRST_NAME column would be dropped provided it does not contain any
data.
B.The FIRST_NAME column would be dropped provided at least one or more columns
remain in the table.
C. The FIRST_NAME column can be rolled back provided the SET UNUSED option
is added to the above SQL statement.
D. The FIRST_NAME column can be dropped even if it is part of a composite
PRIMARY KEY provided the CASCADE option is used.
Answer:B,D

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