Count the size of the table under the user (including large segment statistics)

SELECT *
From (select owner, segment_name, sum (GB)
From (select OWNER, segment_name, bytes/1024/1024/1024 GB
From Dba_segments
where owner = ' USERNAME'
and Segment_type = ' TABLE '
and segment_name not like '%log% '
UNION ALL
Select A.owner, B.table_name, a.bytes/1024/1024/1024 GB
From Dba_segments A, dba_lobs b
where A.owner = ' USERNAME'
and B.owner = ' USERNAME'
and a.segment_name = B.segment_name
and A.segment_type = ' lobsegment '
and b.table_name not like '%log% ') a
Group By owner, Segment_name
ORDER BY 3 Desc) bb
where RowNum < 21