DR,OP 表的时候，其他用户对此表的权限并没用被收回，这样导致重新创建同名的表时，以前其他用户对此表的权限会自动赋予，进而产生 权限外流。因此，在删除表时，要同时取消其他用户在此表上的相应权限。
下面的例子说明了不收回相关访问授权的隐患。
（1）用root创建用户z1，授权对test1下所有表的select权限：
mysql> grant select on test1.* to z1@localhost;
Query OK, 0 rows affected (0.00 sec)
mysql> show grants for z1@localhost;
+-----------------------------------------------+
| Grants for z1@localhost |
+-----------------------------------------------+
| GRANT USAGE ON *.* TO 'z1'@'localhost' |
| GRANT SELECT ON `test1`.* TO 'z1'@'localhost' |
+-----------------------------------------------+
2 rows in set (0.00 sec)（2）z1登录，测试权限：
[root@localhost test1]# mysql -uz1
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 43
Server version: 5.0.41-community-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> use test1
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show tables;
+-----------------+
| Tables_in_test1 |
+-----------------+
| t1 |
| t12 |
| t2 |
+-----------------+
3 rows in set (0.00 sec)（3）root 登录，删除表 t1：
[root@localhost test1]# mysql -uroot
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
[root@localhost test1]# mysql -uroot -p123
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 45
Server version: 5.0.41-community-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> use test1
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> drop table t1;
Query OK, 0 rows affected (0.00 sec)
mysql> exit
Bye（4）z1登录，再次测试权限:
[root@localhost test1]# mysql -uz1
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 46
Server version: 5.0.41-community-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> use test1
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show tables;
+-----------------+
| Tables_in_test1 |
+-----------------+
| t12 |
| t2 |
+-----------------+
2 rows in set (0.00 sec)（5）此时 t1 表已经看不到了。
mysql> show grants for z1@localhost;
+-----------------------------------------------+
| Grants for z1@localhost |
+-----------------------------------------------+
| GRANT USAGE ON *.* TO 'z1'@'localhost' |
| GRANT SELECT ON `test1`.* TO 'z1'@'localhost' |
+-----------------------------------------------+
2 rows in set (0.00 sec)权限仍然显示对test1下所有表的SELECT（安全漏洞）。
（6）root再次登录，创建t1条：
[root@localhost test1]# mysql -uroot -p123
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 48
Server version: 5.0.41-community-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> create table t1(id int);
Query OK, 0 rows affected (0.03 sec)
mysql> exit（7）z1登录，对t1权限依旧存在：
[root@localhost test1]# mysql -uz1 test1
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 49
Server version: 5.0.41-community-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> show tables;
+-----------------+
| Tables_in_test1 |
+-----------------+
| t1 |
| t12 |
| t2 |
+-----------------+
3 rows in set (0.00 sec)
mysql> select * from t1;
Empty set (0.00 sec)注意：对表做删除后，其他用户对此表的权限不会自动收回，一定记住要手工收回。