Add/alter data file in Oracle Db

Add a datafile to a tablespace

Alter tablespace USERS add datafile '/u01/data/users02.dbf' size 5G;

Enable autoextend on for a datafile

Alter database datafile '/u01/data/users02.dbf' autoextend on;

Resize a datafile

alter database datafile '/u01/data/users02.dbf' resize 10G;

Make a datafile offline/online

Alter database datafile '/u01/data/users02.dbf' offline;
Alter database datafile '/u01/data/users02.dbf' online;

Drop a datafile:

Alter tablespace USERS drop datafile '/u01/data/users02.dbf';