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047-098

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-18 14:50:51 0 删除 编辑
98. View the Exhibit and examine the data in EMP and DEPT tables.
In the DEPT table, DEPTNO is the PRIMARY KEY.
In the EMP table, EMPNO is the PRIMARY KEY and DEPTNO is the FOREIGN KEY
referencing the DEPTNO column in the DEPT table.
What would be the outcome of the following statements executed in the given
sequence?
DROP TABLE emp;
FLASHBACK TABLE emp TO BEFORE DROP;
INSERT INTO emp VALUES (2,COTT 10);
INSERT INTO emp VALUES (3,ING 55);
A. Both the INSERT statements would fail because all constraints are
automatically retrieved when the table is flashed back.
B. Both the INSERT statements would succeed because none of the constraints
on the table are automatically retrieved when the table is flashed back.
C. Only the first INSERT statement would succeed because all the constraints
except the primary key constraint are automatically retrieved after a table
is flashed back.
D. Only the second INSERT statement would succeed because all the constraints
except referential integrity constraints that reference other tables are
retrieved automatically after the table is flashed back.
Answer: D
Except:除..外 Referential:参考 integrity:完整
这个题出的很好

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