oracle查詢所有表佔用空間大小____oracle

1
SELECT * FROM
( 
SELECT SEGMENT_NAME, SUM(BYTES)/1024/1024 M
FROM DBA_SEGMENTS 
WHERE OWNER = user
GROUP BY SEGMENT_NAME 
ORDER BY 2 DESC
) 
2 第二種方法
SELECT   partition_name, high_value, high_value_length, tablespace_name,
        pct_free, pct_used, ini_trans, max_trans, initial_extent,
        next_extent, min_extent, max_extent, pct_increase, FREELISTS,
        freelist_groups, LOGGING, BUFFER_POOL, num_rows, blocks,
        empty_blocks, avg_space, chain_cnt, avg_row_len, sample_size,
        last_analyzed
   FROM dba_tab_partitions
  --WHERE table_name = :tname AND table_owner = :towner
ORDER BY partition_position
3 第三種方法


select segment_name, sum(bytes)/1024/1024 Mbytese from user_segments where segment_type='TABLE' group by segment_name;