oracle查询2G以上的表

SELECT a.*, b.comments
  FROM (SELECT OWNER,
               SEGMENT_NAME,
               SEGMENT_TYPE,
               round(SUM(BYTES / 1024 / 1024 / 1024), 3) GB
          FROM DBA_SEGMENTS
         WHERE OWNER IN ('TEST') --and segment_type LIKE 'TABLE%'
         GROUP BY OWNER, SEGMENT_NAME, SEGMENT_TYPE) a,
       dba_tab_comments b
 where a.SEGMENT_NAME = b.table_name
   AND B.owner = A.OWNER
   and a.GB > 2
 ORDER BY 1, 4 DESC;

----取前几个表

SELECT *
  FROM (SELECT a.*, b.comments, ROWNUM RN
          FROM (SELECT OWNER,
                       SEGMENT_NAME,
                       SEGMENT_TYPE,
                       round(SUM(BYTES / 1024 / 1024 / 1024), 3) GB
                  FROM DBA_SEGMENTS
                 WHERE OWNER IN ('PTS') --and segment_type LIKE 'TABLE%'
                 GROUP BY OWNER, SEGMENT_NAME, SEGMENT_TYPE) a,
               dba_tab_comments b
         where a.SEGMENT_NAME = b.table_name
           AND B.owner = A.OWNER
           and a.GB > 2) DD
 WHERE DD.RN < 5
 ORDER BY 1, 4 DESC;