1，查看表空间的使用情况
SELECT A.TABLESPACE_NAME,
ROUND(A.TOTAL_SIZE) "TOTAL_SIZE(MB)",
ROUND(A.TOTAL_SIZE) - ROUND(B.FREE_SIZE, 3) "USED_SIZE(MB)",
ROUND(B.FREE_SIZE, 3) "FREE_SIZE(MB)",
ROUND(B.FREE_SIZE / TOTAL_SIZE * 100, 2) || '%' FREE_RATE
FROM (SELECT TABLESPACE_NAME, SUM(BYTES) / 1024 / 1024 TOTAL_SIZE
FROM DBA_DATA_FILES
GROUP BY TABLESPACE_NAME) A,
(SELECT TABLESPACE_NAME, SUM(BYTES) / 1024 / 1024 FREE_SIZE
FROM DBA_FREE_SPACE
GROUP BY TABLESPACE_NAME) B
WHERE A.TABLESPACE_NAME = B.TABLESPACE_NAME(+)
2.查看建表语句的数据字典
SELECT T1.TABLE_NAME AS 表英文名,
T2.COMMENTS AS 表中文名,
T1.COLUMN_ID AS 字段序号,
T1.COLUMN_NAME AS 字段英文名,
T3.COMMENTS AS 字段中文名,
DECODE(T1.DATA_TYPE,
'NUMBER',
DECODE(T1.DATA_PRECISION,
'',
'INTEGER',
'NUMBER(' || T1.DATA_PRECISION || ',' || T1.DATA_SCALE || ')'),
'TIMESTAMP(6)',
T1.DATA_TYPE,
'DATE',
T1.DATA_TYPE,
T1.DATA_TYPE || '(' || T1.DATA_LENGTH || ')') AS 数据类型
FROM USER_TAB_COLUMNS T1
LEFT JOIN USER_TAB_COMMENTS T2
ON T1.TABLE_NAME = T2.TABLE_NAME
LEFT JOIN USER_COL_COMMENTS T3
ON T1.TABLE_NAME = T3.TABLE_NAME
AND T1.COLUMN_NAME = T3.COLUMN_NAME
ORDER BY T1.TABLE_NAME,T1.COLUMN_ID ASC
