OCP 1Z0 051 QUESTION NO: 1

QUESTION NO: 1

Evaluate the SQL statement:

TRUNCATE TABLE DEPT;

Which three are true about the SQL statement? (Choose three.)

A. It releases the storage space used by the table.

B. It does not release the storage space used by the table.

C. You can roll back the deletion of rows after the statement executes.

D. You can NOT roll back the deletion of rows after the statement executes.

E. An attempt to use DESCRIBE on the DEPT table after the TRUNCATE statement executes will

display an error.

F. You must be the owner of the table or have DELETE ANY TABLE system privileges to truncate

the DEPT table

Answer: A,D,F

delete可以回滚

TEST >create table test as select * from dba_objects;

Table created.

TEST >SELECT bytes FROM User_Segments WHERE segment_name = 'TEST';

BYTES
----------
10485760

1 row selected.

TEST >delete from test where object_id = 5;

1 row deleted.

TEST >rollback;

Rollback complete.

TEST >select object_id from test where object_id = 5;

OBJECT_ID
----------
5

1 row selected.

truncate 可以释放空间，但不能回滚

TEST >truncate table test;

Table truncated.

TEST >SELECT bytes FROM User_Segments WHERE segment_name = 'TEST';

BYTES
----------
65536

1 row selected.

TEST >select object_id from test where object_id = 5;

no rows selected

truncate不是删掉表，当然可以desc

TEST > desc test;
Name           Type          Nullable
-------------- ------------- --------
OWNER          VARCHAR2(30)  Y
OBJECT_NAME    VARCHAR2(128) Y
SUBOBJECT_NAME VARCHAR2(30)  Y
OBJECT_ID      NUMBER        Y
DATA_OBJECT_ID NUMBER        Y
OBJECT_TYPE    VARCHAR2(19)  Y
CREATED        DATE          Y
LAST_DDL_TIME  DATE          Y
TIMESTAMP      VARCHAR2(19)  Y
STATUS         VARCHAR2(7)   Y
TEMPORARY      VARCHAR2(1)   Y
GENERATED      VARCHAR2(1)   Y
SECONDARY      VARCHAR2(1)   Y
NAMESPACE      NUMBER        Y
EDITION_NAME   VARCHAR2(30)  Y

truncate 其它用户的表需要drop any table权限

SCOTT >SELECT * FROM user_sys_privs;

USERNAME                       PRIVILEGE                                ADM
------------------------------ ---------------------------------------- ---
SCOTT                          UNLIMITED TABLESPACE                     NO
SCOTT                          DROP ANY TABLE                           NO

2 rows selected.

SCOTT >truncate table test.test;

Table truncated.

本题答案F的描述有误