整理数据库表说明，偶尔用到，找个地方存一下。。
SELECT t.table_name,(select comments from user_tab_comments where table_name=t.table_name) table_comment,
t.colUMN_NAME,t.DATA_TYPE,t.DATA_LENGTH,
t1.COMMENTS
FROM User_Tab_Cols t, User_Col_Comments t1
WHERE t.table_name = t1.table_name
AND t.column_name = t1.column_name;