https://blog.csdn.net/u013303551/article/details/52354230
SELECT t.table_name,
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;