drop  user 会将该用户的信息全部删掉，而 delete  只会清除user表，其他的比如db表中的信息还是存在。 如果delete 后，再创建一个最小权限的用户，那么他会重用以前的权限。 grant all on test.* to 'test'@'%' identified by 'test'; delete  from user  where  user =test; [b]差看db 表 [/b]mysql> select * from db; +------+---------+------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+ | Host | Db      | User | Select_priv | Insert_priv | Update_priv | Delete_priv | Create_priv | Drop_priv | Grant_priv | References_priv | Index_priv | Alter_priv | Create_tmp_table_priv | Lock_tables_priv | Create_view_priv | Show_view_priv | Create_routine_priv | Alter_routine_priv | Execute_priv | Event_priv | Trigger_priv | +------+---------+------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+ | %    | test    |      | Y           | Y           | Y           | Y           | Y           | Y         | N          | Y               | Y          | Y          | Y                     | Y                | Y                | Y              | Y                   | N                  | N            | Y          | Y            | | %    | test\_% |      | Y           | Y           | Y           | Y           | Y           | Y         | N          | Y               | Y          | Y          | Y                     | Y                | Y                | Y              | Y                   | N                  | N            | Y          | Y            | | %    | test    | test | Y           | Y           | Y           | Y           | Y           | Y         | N          | Y               | Y          | Y          | Y                     | Y                | Y                | Y              | Y                   | Y                  | Y            | Y          | Y            | +------+---------+------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+ 3 rows in set (0.00 sec) test  的权限依然存在 [b]创建一个只有select 的 用户test [/b]grant select  on test.* to 'test'@'%' identified by 'test'; mysql> select * from db; +------+---------+------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+ | Host | Db      | User | Select_priv | Insert_priv | Update_priv | Delete_priv | Create_priv | Drop_priv | Grant_priv | References_priv | Index_priv | Alter_priv | Create_tmp_table_priv | Lock_tables_priv | Create_view_priv | Show_view_priv | Create_routine_priv | Alter_routine_priv | Execute_priv | Event_priv | Trigger_priv | +------+---------+------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+ | %    | test    |      | Y           | Y           | Y           | Y           | Y           | Y         | N          | Y               | Y          | Y          | Y                     | Y                | Y                | Y              | Y                   | N                  | N            | Y          | Y            | | %    | test\_% |      | Y           | Y           | Y           | Y           | Y           | Y         | N          | Y               | Y          | Y          | Y                     | Y                | Y                | Y              | Y                   | N                  | N            | Y          | Y            | | %    | test    | test | Y           | Y           | Y           | Y           | Y           | Y         | N          | Y               | Y          | Y          | Y                     | Y                | Y                | Y              | Y                   | Y                  | Y            | Y          | Y            | +------+---------+------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+ 3 rows in set (0.00 sec) [b]权限和以前的一样。 [/b]