Oracle导出表结构
SELECT B.TABLE_NAME     AS "表名",
       C.COMMENTS       AS "表说明",
       B.COLUMN_ID      AS "字段序号",
       B.COLUMN_NAME    AS "字段名",
       B.DATA_TYPE      AS "字段数据类型",
       B.DATA_LENGTH    AS "数据长度",
       B.DATA_PRECISION AS "整数位",
       B.DATA_SCALE     AS "小数位",
       A.COMMENTS       AS "字段说明"
  FROM ALL_COL_COMMENTS A, ALL_TAB_COLUMNS B, ALL_TAB_COMMENTS C
WHERE A.TABLE_NAME IN (SELECT U.TABLE_NAME FROM USER_ALL_TABLES U)
   AND A.OWNER = B.OWNER
   AND A.TABLE_NAME = B.TABLE_NAME
   AND A.COLUMN_NAME = B.COLUMN_NAME
   AND C.TABLE_NAME = A.TABLE_NAME
   AND C.OWNER = A.OWNER
ORDER BY A.TABLE_NAME, B.COLUMN_ID