1 查看表空间路径

select * from dba_data_files;

2 修改表空间大小

ALTER TABLESPACE MAXDATA ADD DATAFILE '/oradata/XX/MAXDATA02.DBF' SIZE 1000M;

可以通过PL/SQL查看。
1. 查看所有表空间大小
 select tablespace_name,sum(bytes)/1024/1024 from dba_data_files group by tablespace_name; 
2. 未使用的表空间大小 
select tablespace_name,sum(bytes)/1024/1024 from dba_free_space group by tablespace_name; 

补充回答：
查看当前用户每个表占用空间的大小： 
Select   Segment_Name,Sum(bytes)/1024/1024   From   User_Extents   Group   By   Segment_Name

3.创建表空间

-- 创建 DZJC 表空间
CREATE SMALLFILE TABLESPACE "LHCZW" DATAFILE 'F:\oracle\product\10.2.0\oradata\LH\LHCZW' SIZE 100M AUTOEXTEND ON NEXT 100M MAXSIZE UNLIMITED LOGGING EXTENT MANAGEMENT LOCAL SEGMENT SPACE MANAGEMENT AUTO ;
-- 创建 DZJC_INDEX 表空间
CREATE SMALLFILE TABLESPACE "LHCZW_INDEX" DATAFILE 'F:\oracle\product\10.2.0\oradata\LH\LHCZW_index' SIZE 100M AUTOEXTEND ON NEXT 50M MAXSIZE UNLIMITED LOGGING EXTENT MANAGEMENT LOCAL SEGMENT SPACE MANAGEMENT AUTO ;
-- 创建 DZJC_TEMP 表空间
CREATE SMALLFILE TEMPORARY TABLESPACE "LHCZW_TEMP" TEMPFILE 'F:\oracle\product\10.2.0\oradata\LH\LHCZW_temp' SIZE 100M AUTOEXTEND ON NEXT 25M MAXSIZE UNLIMITED EXTENT MANAGEMENT LOCAL UNIFORM SIZE 1M;

-- 创建 DZJC 用户
CREATE USER "LHCZW" PROFILE "DEFAULT" IDENTIFIED BY "123456" DEFAULT TABLESPACE "LHCZW" TEMPORARY TABLESPACE "LHCZW_TEMP" ACCOUNT UNLOCK;
GRANT "CONNECT" TO "LHCZW" WITH ADMIN OPTION;
GRANT "DBA" TO "LHCZW" WITH ADMIN OPTION;