grant 授权
什么是用户授权：在数据库服务器上添加新的连接用户，并设置权限和密码。
为什么要用授权：如果没有授权用户，那么只能有root用户在本机登陆数据库，其它用户无法登陆。
没有授权时，其它主机也无法访问数据库。
指令格式:
mysql> grant 权限列表 on 库名 to 用户名@"客户端地址" identified by "密码" ;
权限列表:
all 所有权限
usage 只能连接上数据库，没有任何权限
select,update,inseret ... 个别权限，这个权限对所有字段有效
select,update(字段1,字段2...) 只能对指定的字段有相应的权
库名:
*.* 所有库所有表
库名.* 一个库
库名.表名 一张表
用户名:
授权时可以自定义,要有标识性,容易记,可以名中看出用途存储在mysql库的user表里
客户端地址:
% 表示互联网上的所有主机0
192.168.4.% 网段内的所有主机
192.168.4.1 1台主机
localhost 数据库服务器本机
授权举例1:
添加admin用户,允许从192.168.4.0/24网段连接,对db3库的user表有查询权限,密码为123456
mysql> grant select on db3.user to admin@"192.168.4.%" identified by "123456";
授权举例2:
添加admin2,允许从本机连接,允许以db3库的所有表有 查询,更新,插入删除记录权限,密码为123456
mysql> grant select ,insert,update,delete on db3.* to admin2@"localhost" identified by "123456";
授权库
grant授权的信息是保存在授权库中的，mysql库记录了授权信息，主要的表如下：
user 记录已有的授权用户及权限
db 记录已有授权用户对数据库的访问权限
tables_priv 记录已有授权用户对表的访问权限
columns_priv 记录已有授权用户对字段的访问权限
一 查看当前columns_priv，tables_priv,db,user表中的授权用户
mysql> select user,host,db,table_name,column_name from mysql.columns_priv; Empty set (0.00 sec) #columns_priv表当前为空，说明当前数据库没有真对某些字段的授权
mysql> select user,host,db,table_name from mysql.tables_priv; +-----------+-----------+-----+------------+ #tables_priv表中只有系统默认的授权用户msyql.sys | user | host | db | table_name | +-----------+-----------+-----+------------+ | mysql.sys | localhost | sys | sys_config | +-----------+-----------+-----+------------+ mysql> select user,host,db from mysql.db; +-----------+-----------+-----+ #db表中也是系统默认授权用户mysql.sys | user | host | db | +-----------+-----------+-----+ | mysql.sys | localhost | sys | +-----------+-----------+-----+ mysql> select user,host from mysql.user; +-----------+-----------+ #user表中有系统默认用户mysql.sys和root | user | host | +-----------+-----------+ | mysql.sys | localhost | | root | localhost | +-----------+-----------+
二 添加真对school.student表中“学号”，“姓名”，“性别”这三个字段的授权用户col_user
mysql> grant select,update(学号,姓名,性别),insert on school.student to col_user@'%' identified by "123456"; mysql> select user,host,db,table_name,column_name from mysql.columns_priv;
#在columns_priv表中查看授权用户,每条记录是一个授权字段 +----------+------+--------+------------+-------------+ | user | host | db | table_name | column_name | +----------+------+--------+------------+-------------+ | col_user | % | school | student | 姓名 | | col_user | % | school | student | 学号 | | col_user | % | school | student | 性别 | +----------+------+--------+------------+-------------+ mysql> select user,host,db,table_name from mysql.tables_priv; +-----------+-----------+--------+------------+ #在tables_priv表中也可以看到该用户对school.student表有访问权限 | user | host | db | table_name | #具体权限需要用show grants查看 +-----------+-----------+--------+------------+ | col_user | % | school | student | | mysql.sys | localhost | sys | sys_config | +-----------+-----------+--------+------------+
mysql> show grants for col_user@'%'; #通过show grants查看col_user对school.student的具体权限
+-----------------------------------------------------------------------------------------------+
| Grants for col_user@% |
+-----------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'col_user'@'%' |
| GRANT SELECT, INSERT, UPDATE (性别, 学号, 姓名) ON `school`.`student` TO 'col_user'@'%' |
+-----------------------------------------------------------------------------------------------+
mysql> select user,host,db from mysql.db; +-----------+-----------+-----+ #db表中看不到该用户 | user | host | db | +-----------+-----------+-----+ | mysql.sys | localhost | sys | +-----------+-----------+-----+ mysql> select user,host from mysql.user; +-----------+-----------+ #在user表中可以看到该用户 | user | host | +-----------+-----------+ | col_user | % | | mysql.sys | localhost | | root | localhost | +-----------+-----------+ mysql>
三 添加授权用户tab_user1,tab_user2对表school.teacher，school.student的访问权限
mysql> grant all on school.teacher to tab_user1@'%' identified by "123456"; mysql> grant select on school.student to tab_user2@'%' identified by "123456"; mysql> select user,host,db,table_name,column_name from mysql.columns_priv;
#colunm_priv表中授权记录的用户没有变化 +----------+------+--------+------------+-------------+ | user | host | db | table_name | column_name | +----------+------+--------+------------+-------------+ | col_user | % | school | student | 姓名 | | col_user | % | school | student | 学号 | | col_user | % | school | student | 性别 | +----------+------+--------+------------+-------------+ #tables_priv表中可以看到tab_user1,tab_user2用户 mysql> select user,host,db,table_name from mysql.tables_priv; +-----------+-----------+--------+------------+ | user | host | db | table_name | +-----------+-----------+--------+------------+ | col_user | % | school | student | | tab_user1 | % | school | teacher | | tab_user2 | % | school | student | | mysql.sys | localhost | sys | sys_config | +-----------+-----------+--------+------------+ mysql> show grants for tab_user1@'%'; #通过show grants可以看出tab_user1,tab_user2的具体授权权限 +---------------------------------------------------------------+ | Grants for tab_user1@% | +---------------------------------------------------------------+ | GRANT USAGE ON *.* TO 'tab_user1'@'%' | | GRANT ALL PRIVILEGES ON `school`.`teacher` TO 'tab_user1'@'%' | +---------------------------------------------------------------+ mysql> show grants for tab_user2@'%'; +-------------------------------------------------------+ | Grants for tab_user2@% | +-------------------------------------------------------+ | GRANT USAGE ON *.* TO 'tab_user2'@'%' | | GRANT SELECT ON `school`.`student` TO 'tab_user2'@'%' | +-------------------------------------------------------+ mysql> select user,host,db from mysql.db; #db表中没有变化 +-----------+-----------+-----+ | user | host | db | +-----------+-----------+-----+ | mysql.sys | localhost | sys | +-----------+-----------+-----+ mysql> select user,host from mysql.user; #user表中可以看到tab_user1,tab_user2 +-----------+-----------+ | user | host | +-----------+-----------+ | col_user | % | | tab_user1 | % | | tab_user2 | % | | mysql.sys | localhost | | root | localhost | +-----------+-----------+ mysql>
四 添加授权用户db_user1,db_user2用户对库school,school2的访问权限
mysql> grant all on school.* to db_user1@'%' identified by "123456"; mysql> grant select on school2.* to db_user2@'%' identified by "123456"; mysql> select user,host,db,table_name,column_name from mysql.columns_priv;
#只要没有对任意表中字段的授权，column_priv表不会有变化 +----------+------+--------+------------+-------------+ | user | host | db | table_name | column_name | +----------+------+--------+------------+-------------+ | col_user | % | school | student | 姓名 | | col_user | % | school | student | 学号 | | col_user | % | school | student | 性别 | +----------+------+--------+------------+-------------+ mysql> select user,host,db,table_name from mysql.tables_priv;
#添加了真对库的授权用户，没有对表的授权用户所以db表中也不会变化 +-----------+-----------+--------+------------+ | user | host | db | table_name | +-----------+-----------+--------+------------+ | col_user | % | school | student | | tab_user1 | % | school | teacher | | tab_user2 | % | school | student | | mysql.sys | localhost | sys | sys_config | +-----------+-----------+--------+------------+ mysql> select user,host,db from mysql.db; #db表中可以看到添加的授权用户 +-----------+-----------+---------+ | user | host | db | +-----------+-----------+---------+ | db_user1 | % | school | | db_user2 | % | school2 | | mysql.sys | localhost | sys | +-----------+-----------+---------+ mysql> select user,host from mysql.user; #只要添加了授权用户user表中都会有记录 +-----------+-----------+ | user | host | +-----------+-----------+ | col_user | % | | db_user1 | % | | db_user2 | % | | tab_user1 | % | | tab_user2 | % | | mysql.sys | localhost | | root | localhost | +-----------+-----------+ mysql> 五 添加授权用户user对所有库和表有访问权限
mysql> grant all on *.* to user@'%' identified by "123456"; mysql> select user,host,db,table_name,column_name from mysql.columns_priv; +----------+------+--------+------------+-------------+ | user | host | db | table_name | column_name | +----------+------+--------+------------+-------------+ | col_user | % | school | student | 姓名 | | col_user | % | school | student | 学号 | | col_user | % | school | student | 性别 | +----------+------+--------+------------+-------------+ 3 rows in set (0.00 sec) mysql> select user,host,db,table_name from mysql.tables_priv; +-----------+-----------+--------+------------+ | user | host | db | table_name | +-----------+-----------+--------+------------+ | col_user | % | school | student | | tab_user1 | % | school | teacher | | tab_user2 | % | school | student | | mysql.sys | localhost | sys | sys_config | +-----------+-----------+--------+------------+ 4 rows in set (0.01 sec) mysql> select user,host,db from mysql.db; +-----------+-----------+---------+ | user | host | db | +-----------+-----------+---------+ | db_user1 | % | school | | db_user2 | % | school2 | | mysql.sys | localhost | sys | +-----------+-----------+---------+ 3 rows in set (0.00 sec) mysql> select user,host from mysql.user; #只有在user表中可以看到use_user +-----------+-----------+ | user | host | +-----------+-----------+ | col_user | % | | db_user1 | % | | db_user2 | % | | tab_user1 | % | | tab_user2 | % | | use_user | % | | mysql.sys | localhost | | root | localhost | +-----------+-----------+ mysql>