使用ALTER TABLE不可以( )

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• 在oracle数据库中，关于使用AlTER TABLE进行修改表的定义，下列描述正确的是？（）

  A . 使用该命令可以修改列的名称 B . 使用该命令可以修改列的数据类型 C . 使用该命令可以修改表的名称 D . 使用该命令可以修改列的精度

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• Examine the following command: SQL> ALTER TABLE booking SHRINK SPACE COMPACT; Which activity is performed when the preceding command is executed?（）

  A . The shrink operation touches every block in the BOOKING table B . The high-water mark (HWM) for the BOOKING table is shifted from its original position C . The progress of the shrink operation is saved in the bitmap blocks of the BOOKING table D . The data manipulation language (DML) triggers on the BOOKING table are executed because the shrink operation is internally handled by the INSERT/DELETE operatio

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• 假设需要导出某个表table1，只导出表结构，不导出数据，可以使用如下（）命令。

  A . EXP user/pwd tables=（name,table1）file=export.dmp Rows=y B . EXP user1/pwd table table1 file=extable1.dmp C . EXP user/pwd tables=（name,table1）file=export.dmp Rows=n D . EXP user1/pwd table=table1 file=extable1.dmp Rows=

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• Consider the following statement on a RANGE partitioned table: ALTER TABLE orders DROP PARTITION p1, p3; What is the outcome of executing the above statement?（）

  A . A syntax error will result as you cannot specify more than one partition in the same statement B . All data in p1 and p3 partitions are removed and the table definition is changed C . All data in p1 and p3 partitions are removed, but the table definition remains unchanged D . Only the first partition (p1) will be dropped as only one can be dropped at any time

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• Before a Flashback Table operation, you execute the following command: ALTER TABLE employees ENABLE ROW MOVEMENT; Why would you need this to be executed?（）

  A . Because row IDs may change during the flashback operation B . Because the object number changes after the flashback operation C . Because the rows are retrieved from the recycle bin during the flashback operation D . Because the table is moved forward and back to a temporary during the flashback opertio

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• You executed the following SQL statement to shrink the EMPLOYEES table segment stored in the EXAMPLE tablespace: ALTER TABLE employees SHRINK SPACE CASCADE; Which statement is correct in this scenario?（）

  A . The EMPLOYEES table will be changed to read-only mode during the shrink operation. B . The indexes created on the EMPLOYEES table will need to be rebuilt after the shrink operation is over. C . The shrink behavior will be cascaded to all dependent segments of the table that support a shrink operation. D . Data manipulation language (DML) operations will not be possible on the EMPLOYEES table during the COMPACTION phase of the shrink operation.

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• Examine the following statement that is used to modify the primary key constraint on the SALES table： SQL> ALTER TABLE SALES MODIFY CONSTRAINT pk DISABLE VALIDATE； Which three statements aretrue regarding the above command（）

  A . The constraint remains valid. B . The index on the constraint is dropped. C . It allows the loading of data into the table using SQL *Loader. D . New data conforms to the constraint， but existing data is not checked. E . It allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.

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• 使用Alter table语句可以（）。

  A、同时修改字段数据类型和长度 B、修改计算列 C、产量 float D、同时删除字段和字段约束

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• Examine the following command：   SQL> ALTER TABLE booking SHRINK SPACE COMPACT；   Which activity is performed when the preceding command is executed？（）

  A .  The shrink operation touches every block in the BOOKING table B .  The high-water mark （HWM） for the BOOKING table is shifted from its original position C .  The progress of the shrink operation is saved in the bitmap blocks of the BOOKING table D .  The data manipulation language （DML） triggers on the BOOKING table are executed because the shrink operation is internally handled by the INSERT/DELETE operatio

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• 默认约束是在CREATE TABLE或ALTER TABLE语句中定义的，删除表的时候默认约束也随之删除了。

  A . 正确 B . 错误

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• Examine the following statement that is used to modify the constraint on the SALES table： SQL> ALTER TABLE SALES MODIFY CONSTRAINT pk DISABLE VALIDATE； Which three statements are true regarding the above command（）

  A . The constraint remains valid. B . The index on the constraint is dropped. C . It allows the loading of data into the table using SQL*Loader. D . New data conforms to the constraint， but existing data is not checked E . It allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.

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• Which two data types can be converted to LOBs using an ALTER TABLE… MODIFY command？（）

  A . RAW B . LONG C . VARCHAR D . LONG RAW

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• 在ALTER TABLE中，（）用来添加新字段；（）用来修改已有字段。

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• 在oracle数据库中，一张表通过带有INITIALLY IMMEDIATE的语句来创建，通过执行ALTER TABLE来启用之前关闭的VALIDATE功能，下面那两项描述了该语句的印象？（）

  A . 如果存在有违反约束的行将执行失败 B . 将启用约束验证从事物的开始到结束 C . 在该表上将阻止insert，update，delete操作，如果操作违反约束的数据 D . 不验证已经存在表中的数据

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• Which of the following commands should be used to alter the routing table on a running system without affecting the ODM settings？（）

  A . inetd B . route C . cfgmgr D . chdev

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• You executed the following SQL statement to shrink the EMPLOYEES table segment stored in the EXAMPLE tablespace: ALTER TABLE employees SHRINK SPACE CASCADE; Which statement is correct in this scenario?（）

  A . The data in the segment will be compacted but the high water mark will not be adjusted  B . The EMPLOYEES table will be changed to read-only mode during the shrink operation  C . The indexes created on the EMPLOYEES table will need to be rebuilt after the shrink operation is over D . The shrink behavior will be cascaded to all dependent segments of the table that support a shrink operation  E . Data manipulation language (DML) operations will not be possible on the EMPLOYEES table during the COMPACTION phase of the shrink operatio

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• You are shrinking the SCOTT.EMP table by executing the ALTER TABLE SCOTT.EMP SHRINK SPACE CASCADE statement. What is a prerequisite for shrinking the SCOTT.EMP table？（）

  A .  You must enable the block change tracking feature. B .  You must have enable the flashback feature. C .  You must use the OMF in your database. D .  You must define the tablespace of the SCOTT.EMP table for automatic segment space management.

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• 在ALTER TABLE中，指定某列不可用，可是使用哪个关键字？（）

  A . UNUSED B . SET UNUSED C . DISABLE D . NOUSE

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• Before a Flashback Table operation，you execute the following command：   ALTER TABLE employees ENABLE ROW MOVEMENT；   Why would you need this to be executed？（）  

  A .  Because row IDs may change during the flashback operation B .  Because the object number changes after the flashback operation C .  Because the rows are retrieved from the recycle bin during the flashback operation D .  Because the table is moved forward and back to a temporary during the flashback opertio

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• 有如下三步操作,并且均成功执行,请选择结果（） delete from emp; alter table emp add(addr varchar2(40)); rollback;

  A . emp表中数据处于回滚段中 B . emp表中的数据被永久删除 C . emp表中的数据没有变化 D . 原来的emp表中的数据被添加到新emp表中 E . 以上所述都不正确

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• 更改“成绩表”为列“column_b”设置“UNIQUE”约束。 ALTER TABLE 成绩表 ADD column_b VARCHAR(20) NULL CONSTRAINT b_unique UNIQUE

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• 在“学生”表中删除“备注”字段 ：ALTER TABLE 学生 __________ 备注

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• alter table语句可以用于在已有的表中添加、删除或修改列。（)

  是 否

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• Before a Flashback Table operation, you execute the following command:ALTER TABLE employees ENABLE ROW MOVEMENT;Why would you need this to be executed？（）

  A. Because row IDs may change during the flashback operation B. Because the object number changes after the flashback operation C. Because the rows are retrieved from the recycle bin during the flashback operation D. Because the table is moved forward and back to a temporary during the flashback operation

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