You execute this command to drop the ITEM table， which has the primary key referred in the ORDERtable： 
SQL> DROP TABLE scott.item CASCADE CONSTRAINTS PURGE； 
Which two statements are true about the effect of the command（）

多项选择题WhichthreedescriptionsarecorrectabouttheeffectsoftheTRUNCATEcommandonatable（）

A.The corresponding indexes for the table are also truncated.
B.Delete triggers on the table are fired during the execution of the TRUNCATE command.
C.The child table is truncated when the TRUNCATE command is applied on the parent table.
D.The high-water mark （HWM） is set to point to the first usable data block in the table segment.
E.No undo or very little undo data is generated during the execution of the TRUNCATE command

单项选择题Which statement is true about the PCTFREE setting for the table（）

A.It sets the minimum percentage of a data block to be reserved to contain chained rows from other blocks.
B.It sets the minimum percentage of a data block to be reserved as free space before the server prevents inserts into the block.
C.It sets the minimum percentage of a data block to be reserved to contain the bitmap used to maintain the free block information.
D.It sets the minimum percentage of a block that can be used for row data plus overhead before new rows are added to the block.

多项选择题Examine the command that is used to create a table：  SQL> CREATE TABLE orders（oid NUMBER（6） PRIMARY KEY， odate DATE， ccode NUMBER（6）， oamt NUMBER（10，2）） TABLESPACE users；  Which two statements are true about the effect of the above command） （）

A.A CHECK constraint is created on the OID column.
B.A NOT NULL constraint is created on the OID column.
C.The ORDERS table is the only object created in the USERS tablespace.
D.The ORDERS table and a unique index are created in the USERS tablespace.
E.The ORDERS table is created in the USERS tablespace and a unique index is created on the OIDcolumn in the SYSTEM tablespace.

单项选择题You want to access employee details contained in flat files as part of the EMPLOYEE table. You planto add a new column to the EMPLOYEE table to achieve this.  Which data type would you use for the new column（）

A.CLOB
B.BLOB
C.BFILE
D.LONG RAW

单项选择题You created a profile APP_USER and assigned it to the users. After a month， you decide to drop theprofile.Some user sessions are currently connected to the database instance and are using the APP_USERprofile. This command is used to drop the profile： SQL> DROP PROFILE app_user；  Which statement describes the result（）

A.The command produces an error.
B.The profile is dropped and current user sessions use the DEFAULT profile immediately.
C.The profile is dropped and only the subsequent user sessions use the DEFAULT profile.
D.The profile is dropped， the sessions are terminated， and the subsequent user sessions use theDEFAULT profile.