十三周五次课

Posted 2020-10-28

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十三周五次课

13.4mysql用户管理

13.5常用sql语句

13.6MySQL数据库备份恢复

13.4MySQL用户管理

mysql用户管理目录概要

grant all on . to 'user1' identified by 'passwd';
grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'192.168.133.1' identified by 'passwd';
grant all on db1.* to 'user3'@'%' identified by 'passwd';
show grants;
show grants for [email protected];

mysql用户管理

场景，为了安全，新建的站点，创建新的用户，或者给予使用已有账户，给予权限
grant all on . to 'user1' identified by 'passwd';

grant 表示授权
all 表示所有权限，查看，创建，删除等等
on . to 'user1' identified by 'passwd';

若是登录到mysql中后，输错了字符，并按了回车键，直接输入分号 ; 就会推出，回到mysql的命令行
退出mysql除了使用 quit 命令，还可以使用 exit 命令，还可以ctrl+d快捷键退出

1.登录到mysql

[[email protected] ~]# mysql -uroot -p

Enter password:

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 1

Server version: 5.6.35 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

2.创建普通用户user1，命令

命令grant all on . to 'user1'@'127.0.0.1' identified by '123456a';——>在输入命令的时候，千万要注意符号，一旦漏失了符号 ' '，那么后面就无法登录到user1的mysql

第一个 * 表示库名，可以写成mysql.* 那就表示对mysql所有的表
'user1'@'127.0.0.1' 指定用户@指定来源IP （指定用户可以写 % 就是通配，表示所有的IP）如果指定了来源IP，那么只能通过来源IP登录
符号*.* 表示所有库，所有表
identified by 'passwd' 指定user1的mysql密码

grant语句，是不会记录到命令历史中的因为不安全

mysql> grant all on *.* to 'user1'@'127.0.0.1' identified by '123456a';

Query OK, 0 rows affected (0.00 sec)

mysql>

3.退出数据库，并尝试user1是否可以登录

[[email protected] ~]# mysql -uuser1 -p'123456a'

Warning: Using a password on the command line interface can be insecure.

ERROR 1045 (28000): Access denied for user 'user1'@'localhost' (using password: YES)

[[email protected] ~]#

4.会看到登录失败，因为它默认的是sock，需要指定 -h 指定IP，会看到成功登录到user1的数据库

[[email protected] ~]# mysql -uuser1 -p123456a -h127.0.0.1

Warning: Using a password on the command line interface can be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 3

Server version: 5.6.35 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> quit

Bye

[[email protected] ~]#

5.授权localhost，授权本地，用sock去连接

6.重新登录root，并输入localhost，创建成功后，并退出

grant all on . to 'user1'@'localhost' identified by '123456a';

[[email protected] ~]# mysql -uroot -paminglinux

Warning: Using a password on the command line interface can be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 4

Server version: 5.6.35 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> grant all on *.* to 'user1'@'localhost' identified by '123456a';

Query OK, 0 rows affected (0.00 sec)

mysql> quit

Bye

[[email protected] ~]#

7.这时不加-h 也可以登录到user1了，因为现在授权就是针对localhost，localhost就是针对的sock

[[email protected] ~]# mysql -uuser1 -p123456a

Warning: Using a password on the command line interface can be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 5

Server version: 5.6.35 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> exit

Bye

[[email protected] ~]#

8.退出数据库除了用 quit 命令，还可以用 exit 命令，还可以ctrl+d快捷键退出

针对具体的权限去授权

grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'192.168.133.1' identified by 'passwd';

针对SELECT,UPDATE,INSERT，针对 db1这个库所有的表给用户user2来源IP，并设定密码

grant all on db1.* to 'user3'@'%' identified by 'passwd';

针对所有的IP去授权

show grants; 查看所有的授权

在登录到某一用户下，show grants;会查看到当前用户的权限的
登录user1用户的mysql，去查看授权

[[email protected] ~]# mysql -uuser1 -p123456a

Warning: Using a password on the command line interface can be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 6

Server version: 5.6.35 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show grants;

+-----------------------------------------------------------------------------------------------------------------------+

| Grants for [email protected] |

+-----------------------------------------------------------------------------------------------------------------------+

| GRANT ALL PRIVILEGES ON *.* TO 'user1'@'localhost' IDENTIFIED BY PASSWORD '*B012E8731FF1DF44F3D8B26837708985278C3CED' |

+-----------------------------------------------------------------------------------------------------------------------+

1 row in set (0.00 sec)

mysql>

show grants for user1@127.0.0.1; 指定用户去查看授权

登录root用户的mysql，然后查看user1用户的mysql的授权

[[email protected] ~]# mysql -uroot -paminglinux

Warning: Using a password on the command line interface can be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 7

Server version: 5.6.35 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show grants for [email protected]'127.0.0.1';

+-----------------------------------------------------------------------------------------------------------------------+

| Grants for [email protected] |

+-----------------------------------------------------------------------------------------------------------------------+

| GRANT ALL PRIVILEGES ON *.* TO 'user1'@'127.0.0.1' IDENTIFIED BY PASSWORD '*B012E8731FF1DF44F3D8B26837708985278C3CED' |

+-----------------------------------------------------------------------------------------------------------------------+

1 row in set (0.01 sec)

mysql>

show grants;需求

show grants；看的是root

1.创建一个用户user2，并做一个授权

grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'192.168.133.1' identified by 'passwd';

mysql> grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'192.168.133.1' identified by 'passwd';

Query OK, 0 rows affected (0.05 sec)

mysql>

2.查看user2的授权

show grants for [email protected]'192.168.133.1';

mysql> show grants for [email protected]'192.168.133.1';

+------------------------------------------------------------------------------------------------------------------+

| Grants for [email protected] |

+------------------------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'user2'@'192.168.133.1' IDENTIFIED BY PASSWORD '*59C70DA2F3E3A5BDF46B68F5C8B8F25762BCCEF0' |

| GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user2'@'192.168.133.1' |

+------------------------------------------------------------------------------------------------------------------+

2 rows in set (0.00 sec)

mysql>

3.有一种情况会用到它，比如说，给192.168.133.1做了授权了，但发现一个IP不够，还有一个192.168.133.2，也就是说user2用户不仅需要在192.168.133.1上登录，还需要在192.168.133.2上登录，这时候就需要把授权的命令全部在执行一遍

4.这时候就可以直接把GRANT USAGE ON *.* TO 'user2'@'192.168.133.1' IDENTIFIED BY PASSWORD '*59C70DA2F3E3A5BDF46B68F5C8B8F25762BCCEF0'复制一遍，将其中192.168.133.1改为192.168.133.2 并在语句结尾加上分号 ;

mysql> GRANT USAGE ON *.* TO 'user2'@'192.168.133.2' IDENTIFIED BY PASSWORD '*59C70DA2F3E3A5BDF46B68F5C8B8F25762BCCEF0';

Query OK, 0 rows affected (0.00 sec)

mysql>

5.然后再将第二行复制GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user2'@'192.168.133.1',把IP改为192.168.133.2，并加上分号 ;

mysql> GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user2'@'192.168.133.2';

Query OK, 0 rows affected (0.00 sec)

mysql>

6.这时候在来查看show grants查看192.168.133.2

mysql> show grants for [email protected]'192.168.133.2';

+------------------------------------------------------------------------------------------------------------------+

| Grants for [email protected] |

+------------------------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'user2'@'192.168.133.2' IDENTIFIED BY PASSWORD '*59C70DA2F3E3A5BDF46B68F5C8B8F25762BCCEF0' |

| GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user2'@'192.168.133.2' |

+------------------------------------------------------------------------------------------------------------------+

2 rows in set (0.00 sec)

mysql>

7.show grants;会看到同样的密码，同样的用户，唯一改变的就是IP

8.在知道mysql的用户名，但不知道密码，也可以这样去授权

13.5 常用sql语句

常用sql语句目录概要

select count(*) from mysql.user;
select * from mysql.db;
select db from mysql.db;
select db,user from mysql.db;
select * from mysql.db where host like '192.168.%';
insert into db1.t1 values (1, 'abc');
update db1.t1 set name='aaa' where id=1;
truncate table db1.t1;
drop table db1.t1;
drop database db1;

常用sql语句

增删改查，就是mysql和其他关系型数据库常用的select语句操作命令

查询语句

1.首先登录root下的mysql

[[email protected] ~]# mysql -uroot -paminglinux

Warning: Using a password on the command line interface can be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 4

Server version: 5.6.35 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

2.使用db1库

mysql> use db1

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>

3.查看当前库的所有表show tables;

mysql> show tables;

+---------------+

| Tables_in_db1 |

+---------------+

| t1 |

+---------------+

1 row in set (0.00 sec)

mysql>

4.查看表的行数 select count(*) from mysql.user;

库和表中间有个分割符，就是用点 . 分割

mysql> select count(*) from mysql.user;

+----------+

| count(*) |

+----------+

| 10 |

+----------+

1 row in set (0.02 sec)

mysql>

就是说user表有10行内容
虽然已经进入了db1数据库，仍然可以查询mysql数据库的表

5.查看所有的内容 select * from mysql.db;（这样看起来会很乱） ——>可以在后面加上\G，如select * from mysql.db\G;

这里的 * 表示查看所有内容，但是不建议使用，因为这样很耗费资源和时间

mysql> select * from mysql.db\G;

*************************** 1. row ***************************

Host: %

Db: test

User:

Select_priv: Y

Insert_priv: Y

Update_priv: Y

Delete_priv: Y

Create_priv: Y

Drop_priv: Y

Grant_priv: N

References_priv: Y

Index_priv: Y

Alter_priv: Y

Create_tmp_table_priv: Y

Lock_tables_priv: Y

Create_view_priv: Y

Show_view_priv: Y

Create_routine_priv: Y

Alter_routine_priv: N

Execute_priv: N

Event_priv: Y

Trigger_priv: Y

*************************** 2. row ***************************

//下面省略了很多

6.查看db库的所有内容 select db from mysql.db; 第一个db是字段

mysql> select db from mysql.db;

+---------+

| db |

+---------+

| test |

| test\_% |

| db1 |

+---------+

4 rows in set (0.00 sec)

mysql>

7.查db字段和user字段 select db,user from mysql.db;

mysql> select db,user from mysql.db;

+---------+-------+

| db | user |

+---------+-------+

| test | |

| test\_% | |

| db1 | user2 |

+---------+-------+

4 rows in set (0.00 sec)

mysql>

8.模糊查询 select * from mysql.db where host like '192.168.%';

like 就是模糊匹配

mysql> select * from mysql.db where host like '192.168.%'\G;

*************************** 1. row ***************************

Host: 192.168.133.1

Db: db1

User: user2

Select_priv: Y

Insert_priv: Y

Update_priv: Y

Delete_priv: N

Create_priv: N

Drop_priv: N

Grant_priv: N

References_priv: N

Index_priv: N

Alter_priv: N

Create_tmp_table_priv: N

Lock_tables_priv: N

Create_view_priv: N

Show_view_priv: N

Create_routine_priv: N

Alter_routine_priv: N

Execute_priv: N

Event_priv: N

Trigger_priv: N

*************************** 2. row ***************************

Host: 192.168.133.2

Db: db1

User: user2

Select_priv: Y

Insert_priv: Y

Update_priv: Y

Delete_priv: N

Create_priv: N

Drop_priv: N

Grant_priv: N

References_priv: N

Index_priv: N

Alter_priv: N

Create_tmp_table_priv: N

Lock_tables_priv: N

Create_view_priv: N

Show_view_priv: N

Create_routine_priv: N

Alter_routine_priv: N

Execute_priv: N

Event_priv: N

Trigger_priv: N

2 rows in set (0.00 sec)

ERROR:

No query specified

mysql>

插入语句

1.查看创建的表

mysql> desc db1.t1;

+-------+----------+------+-----+---------+-------+

+-------+----------+------+-----+---------+-------+

| id | int(4) | YES | | NULL | |

+-------+----------+------+-----+---------+-------+

2 rows in set (0.00 sec)

mysql>

2.查看db1.t1表的内容，会发现为空

mysql> select * from db1.t1;

Empty set (0.00 sec)

mysql>

3.插入数据到 insert into db1.t1 values (1, 'abc');

插入1, 'abc'到db1.t1表

mysql> insert into db1.t1 value (1,'abc');

Query OK, 1 row affected (0.02 sec)

4.再来查询db1.t1

mysql> select * from db1.t1;

+------+------+

| id | name |

+------+------+

| 1 | abc |

+------+------+

1 row in set (0.00 sec)

mysql>

5.这样就成功了插入了一条数据，在插入的时候 name 这个字段应该是是一个字符串，字符串需要加上一个单引号 ' ' ，数字可以不加单引号

mysql> insert into db1.t1 value (1,234);

Query OK, 1 row affected (0.00 sec)

mysql> select * from db1.t1;

+------+------+

| id | name |

+------+------+

| 1 | abc |

| 1 | 234 |

+------+------+

2 rows in set (0.00 sec)

mysql> insert into db1.t1 value (1,'234');

Query OK, 1 row affected (0.00 sec)

mysql> select * from db1.t1;

+------+------+

| id | name |

+------+------+

| 1 | abc |

| 1 | 234 |

+------+------+

3 rows in set (0.00 sec)

mysql>

6.这里没有做限制，这里id和name都可以是相同的，同一个字段里有相同的数字，相同的值

7.也可以做一些限制，在插入相同的id的时候，就会冲突

update操作

更改db1.t1表的字符串为name 的数据和字符串为id 的数据
update db1.t1 set name='aaa' where id=1;

mysql> update db1.t1 set name='aaa' where id=1;

Query OK, 3 rows affected (0.00 sec)

Rows matched: 3 Changed: 3 Warnings: 0

mysql> select * from db1.t1;

+------+------+

| id | name |

+------+------+

| 1 | aaa |

+------+------+

3 rows in set (0.00 sec)

mysql>

mysql> update db1.t1 set id=2 where name='aaa';

Query OK, 3 rows affected (0.00 sec)

Rows matched: 3 Changed: 3 Warnings: 0

mysql> select * from db1.t1;

+------+------+

| id | name |

+------+------+

| 2 | aaa |

+------+------+

3 rows in set (0.00 sec)

mysql>

delete操作

删除db1.t1表的数据和字符串为id 的数据
delete from db1.t1 where id=1;

mysql> delete from db1.t1 where id=2;

Query OK, 3 rows affected (0.00 sec)

mysql> select * from db1.t1;

Empty set (0.00 sec)

mysql> insert into db1.t1 values (1,'234');

Query OK, 1 row affected (0.00 sec)

mysql> select * from db1.t1;

+------+------+

| id | name |

+------+------+

| 1 | 234 |

+------+------+

1 row in set (0.00 sec)

truncate清空一个表

清空表数据 truncate table db1.t1;

即使表的数据清空了，但表的字段依旧存在的

mysql> truncate db1.t1;

Query OK, 0 rows affected (0.03 sec)

mysql> select * from db1.t1;

Empty set (0.00 sec)

mysql> desc db1.t1;

+-------+----------+------+-----+---------+-------+

+-------+----------+------+-----+---------+-------+

| id | int(4) | YES | | NULL | |

+-------+----------+------+-----+---------+-------+

2 rows in set (0.00 sec)

mysql>

truncate 只是清空的内容，而drop 会清空表的数据并清除表的框架
drop 会把表的框架也丢掉 drop table db1.t1;

mysql> drop table db1.t1;

Query OK, 0 rows affected (0.01 sec)

mysql> select * from db1.t1;

ERROR 1146 (42S02): Table 'db1.t1' doesn't exist //因为表的架构已经不存在了

mysql>

丢掉表 drop database db1;

总结

在使用mysql的时候，少用 * 这样的操作，因为若是一个表里面的内容很多，select count(*)这样操作就会很耗时，浪费资源
数据库中常用引擎是myisam和innodb，默认mysql库里面都是使用的myisam引擎

use db1
show create table t1;
在select count(*)查看表的时候会很快
use mysql;
show create table user\G;
特点：myisam引擎，能自动去统计有多少行
特点：innodb引擎，不会自动统计行数，每次去查询，每次去统计行数，就会很耗时
所以select count(*)这种操作尽量减少，会耗费太多资源

13.6 mysql数据库备份恢复

mysql数据库备份恢复目录概要

备份库 mysqldump -uroot -p123456 mysql > /tmp/mysql.sql
恢复库 mysql -uroot -p123456 mysql < /tmp/mysql.sql

备份表 mysqldump -uroot -p123456 mysql user > /tmp/user.sql
恢复表 mysql -uroot -p123456 mysql < /tmp/user.sql
备份所有库 mysqldump -uroot -p -A >/tmp/123.sql
只备份表结构 mysqldump -uroot -p123456 -d mysql > /tmp/mysql.sql

mysql数据库备份恢复

备份库

1.在执行mysqldump -uroot -p123456 mysql的时候会看到很多信息，屏幕上显示的这些就是备份的数据

2.备份数据库

[[email protected] ~]# mysqldump -uroot -paminglinux mysql > /tmp/mysqlbak.sql

Warning: Using a password on the command line interface can be insecure.

[[email protected] ~]#

3.我们可以通过mysqlbak.sql来恢复数据库，还可以恢复到另外一个数据库里面去

4.创建一个新的库mysql2

[[email protected] ~]# mysql -uroot -paminglinux -e "create database mysql2"

Warning: Using a password on the command line interface can be insecure.

[[email protected] ~]#

5.恢复库

mysql -uroot -phanfeng mysql < /tmp/mysql.sql

[[email protected] ~]# mysql -uroot -paminglinux mysql2 < /tmp/mysqlbak.sql

Warning: Using a password on the command line interface can be insecure.

6.进入到数据库里面，在后面加一个mysql2 就会进入到mysql2数据库里面

mysql -uroot -p'hanfeng' mysql2

[[email protected] ~]# mysql -uroot -paminglinux mysql2

Warning: Using a password on the command line interface can be insecure.

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 10

Server version: 5.6.35 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

7.查看数据库

mysql> select database();

+------------+

| database() |

+------------+

| mysql2 |

+------------+

1 row in set (0.00 sec)

mysql> show tables;

+---------------------------+

| Tables_in_mysql2 |

+---------------------------+

| columns_priv |

| db |

| event |

| func |

| general_log |

| help_category |

| help_keyword |

| help_relation |

| help_topic |

| innodb_index_stats |

| innodb_table_stats |

| ndb_binlog_index |

| plugin |

| proc |

| procs_priv |

| proxies_priv |

| servers |

| slave_master_info |

| slave_relay_log_info |

| slave_worker_info |

| slow_log |

| tables_priv |

| time_zone |

| time_zone_leap_second |

| time_zone_name |

| time_zone_transition |

| time_zone_transition_type |

| user |

+---------------------------+

28 rows in set (0.00 sec) //28行

mysql> use mysql //进入mysql数据库

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_mysql |

+---------------------------+

| columns_priv |

| db |

| event |

| func |

| general_log |

| help_category |

| help_keyword |

| help_relation |

| help_topic |

| innodb_index_stats |

| innodb_table_stats |

| ndb_binlog_index |

| plugin |

| proc |

| procs_priv |

| proxies_priv |

| servers |

| slave_master_info |

| slave_relay_log_info |

| slave_worker_info |

| slow_log |

| tables_priv |

| time_zone |

| time_zone_leap_second |

| time_zone_name |

| time_zone_transition |

| time_zone_transition_type |

| user |

+---------------------------+

28 rows in set (0.00 sec) //同样是28行

mysql>

备份表

针对库里面的某一个表去做备份，只需要在库后面加上表名字即可备份

先库在表，中间是空格
备份表 mysqldump -uroot -pamignlinux mysql user > /tmp/user.sql

能看到备份的时候，库存在的话，先把库drop掉，然后创建库，表存在的话，先把表drop掉，然后创建表，然后在一步一步的插入每一行数据

[[email protected] ~]# mysql -uroot -paminglinux mysql user > /tmp/user.sql

Warning: Using a password on the command line interface can be insecure.

[[email protected] ~]# less /tmp/user.sql //查看备份表

恢复表的时候，只需要写库的名字，不需要去写表的名字

恢复表 mysql -uroot -paminglinux mysql2 < /tmp/user.sql

恢复mysql2库里面的表

[[email protected] ~]# mysql -uroot -paminglinux mysql2 < /tmp/user.sql

Warning: Using a password on the command line interface can be insecure.

备份所有的库

备份所有库 mysqldump -uroot -paminglinux -A >/tmp/123.sql

-A 表示all所有的意思

[[email protected] ~]# mysqldump -uroot -paminglinux -A > /tmp/mysql_all.sql

Warning: Using a password on the command line interface can be insecure.

[[email protected] ~]#

[[email protected] ~]# less /tmp/mysql_all.sql

搜索Current Database:，结果如下：

Current Database: `db1`

Current Database: `mysql`

Current Database: `mysql2`

Current Database: `test`

只备份表结构 mysqldump -uroot -paminglinux -d mysql > /tmp/mysql.sql

不需要表的数据，只需要表的语句

备份mysql2的表结构

[[email protected] ~]# mysqldump -uroot -paminglinux -d mysql2 > /tmp/mysql2.sql

Warning: Using a password on the command line interface can be insecure.

[[email protected] ~]# less /tmp/mysql2.sql

示例

两个机器的库备份，一个库备份到另一台机器上
解决：

首先两台机器能够通信
然后mysqldump -h 远程mysql-ip -uuser-ppassword dbname > /本地backup.sql
这样即可备份

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