Disk Space

SELECT tablespace_name,

       ROUND(SUM(bytes) / 1024 / 1024) "Size (MB)",

       ROUND(SUM(maxbytes) / 1024 / 1024) "Max Size (MB)",

       ROUND((SUM(maxbytes) - SUM(bytes)) / 1024 / 1024) "Free Space (MB)"

FROM dba_data_files

GROUP BY tablespace_name;