prompt <h3>Détail du tablespace UNDO : </h3>

select /* db-html-report */
    a.tablespace_name,
    a.file_id,
    a.bytes / 1024 / 1024 AS size_mb,
    a.autoextensible,
    b.bytes_free / 1024 / 1024 AS free_mb,
    (a.bytes - b.bytes_free) / 1024 / 1024 AS used_mb,
    ROUND(((a.bytes - b.bytes_free) / a.bytes) * 100, 2) AS pct_used
FROM
    dba_data_files a
JOIN
    (SELECT file_id, SUM(bytes) AS bytes_free
     FROM dba_free_space
     GROUP BY file_id) b
ON a.file_id = b.file_id
WHERE a.tablespace_name like 'UNDO%';