多项选择题
A.DROP USER SMITH；
B.DROP TABLE EMPLOYEES；
C.DROP TABLESPACE USERS；
D.ALTER TABLE SALES_REP DROP PARTITION P1；
E.ALTER TABLE EMPLOYEES DROP COLUMN DESIG_ID；
多项选择题 View this parameter setting in your database： DB_CREATE_FILE_DEST=’D： \oracle\product\10.2.0\oradata\oracle’ You created a tablespace by using this command： CREATE TABLESPACE USERS； Which two statements are true about the USERS tablespace？（）
单项选择题 Your database is in NOARCHIVELOG mode and a logswitch happens every 20 minutes. On Thursday morning，media failure resulted in corruption of a data file belonging to the TOOLS tablespace. Backups are taken on every Sunday. What would you do in this situation？（）
单项选择题 Your database is running under automatic undo management and the UNDO_RETENTION parameter is set to 900 sec. You executed the following command to enable retention guarantee： SQL> ALTER TABLESPACE undotbs1 RETENTION GUARANTEE； What effect would this statement have on the database？（）