OCP 1Z0 052 143

143. You execute a command to resize a data file, sales.dbf, of size 200 MB in your database: 
ALTER DATABASE DATAFILE '/remorse/sales.dbf' RESIZE 150M; 
Which statement is true about this command? 
A.The command must be issued in MOUNT state. 
B.The command succeeds only if the data file is offline. 
C.The command must be issued when the database is in the archivelog mode. 
D.The  command  succeeds  if  no  extent  in  the  tablespace  is  currently  allocated  above  the  150  MB 
boundary of the file. 
Answer: D

同书架一样。书架的宽度不是以书的总长度为准，而是最后一本书的位置。
要把书架变窄，就要先移动最后一本书的位置（move table）

RESIZE Specify RESIZE if you want Oracle Database to attempt to increase or decrease the size of the data file to the specified absolute size in bytes. There is no default, so you must specify a size.

If sufficient disk space is not available for the increased size, or if the file contains data beyond the specified decreased size, then Oracle Database returns an error.