SELECT SEGMENT_NAME, SUM(BYTES) / 1024 / 1024 MBYTESE FROM USER_SEGMENTS WHERE SEGMENT_TYPE = ‘TABLE‘ GROUP BY SEGMENT_NAME;
结果：
SEGMENT_NAME MBYTESE
XXXX 0.0625
XXXX 0.0625
原文：http://www.cnblogs.com/recognition/p/5344566.html