select tablespace_name, sum(bytes)/1024/1024 from dba_data_files group by tablespace_name;

select tablespace_name, sum(bytes)/1024/1024 from dba_free_space group by tablespace_name;

select * from dba_data_files t where t.tablespace_name = 'USERS'

/home/oracle/app/oradata/orcl/users01.dbf

1. select dbf.tablespace_name,  
2. dbf.totalspace "总量(M)",  
3. dbf.totalblocks as 总块数,  
4. dfs.freespace "剩余总量(M)",  
5. dfs.freeblocks "剩余块数",  
6. (dfs.freespace / dbf.totalspace) * 100 "空闲比例"
7. from (select t.tablespace_name,  
8. sum(t.bytes) / 1024 / 1024 totalspace,  
9. sum(t.blocks) totalblocks  
10. from dba_data_files t  
11. group by t.tablespace_name) dbf,  
12. (select tt.tablespace_name,  
13. sum(tt.bytes) / 1024 / 1024 freespace,  
14. sum(tt.blocks) freeblocks  
15. from dba_free_space tt  
16. group by tt.tablespace_name) dfs  
17. where trim(dbf.tablespace_name) = trim(dfs.tablespace_name)