MySQL常用操作(3)MySQL创建用户及授权，常用SQL语句(增删改查)，MySQL数据库的备份与恢复
MySQL创建用户及授权
grant all on *.* to 'user1' identified by 'passwd';
创建user1用户，指定密码，针对所有库所有表指定所有权限
grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'12.19.23.13' identified by 'passwd';
创建user2用户，指定密码，指定来源IP，针对db1库的所有表指定特定权限
grant all on db1.* to 'user3'@'%' identified by 'passwd';
创建user3用户，指定密码，指定来源IP为所有ip，针对db1库的所有表指定所有权限
grant all on db1.* to 'user4'@'localhost' identified by 'passwd';
创建user4用户，指定密码，指定来源IP为localhost，针对db1库的所有表指定所有权限
show grants;
查看当前用户授权
show grants for [email protected]; 查看指定用户user2在指定来源的授权
用于在不知道用户密码时给同一个用户指定多个ip并保持密码权限一致
例：
[root@aliyun ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.6.40 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
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' identified by '123456'
创建user1，指定密码，针对所有库的所有表（*.*）指定所有授权（all）
-> ;
当忘记输入；号的时候，直接在下一行输入同样有效
Query OK, 0 rows affected (0.00 sec)
mysql> grant all on db1.t1 to 'user2'@'127.0.0.1' identified by '123456';
创建user2，指定密码，指定来源ip，针对db1库的t1表指定所有授权
Query OK, 0 rows affected (0.00 sec)
mysql> grant all on db1.* to 'user3'@'%' identified by '678678';
创建用户user3，指定密码，指定来源ip为所有ip，针对db1库的所有表指定所有授权
Query OK, 0 rows affected (0.00 sec)
mysql> grant SELECT,UPDATE,INSERT on db1.* to 'user4'@'12.19.23.13' identified by '456456';
创建user4指定密码指定来源ip，针对db1库的所有表指定特定权限
Query OK, 0 rows affected (0.00 sec)
mysql> grant all on *.* to 'user5'@'localhost' identified by '678123';
创建user5用户指定密码，指定来源IP为local host，针对所有库的所有表指定所有权限
Query OK, 0 rows affected (0.00 sec)
mysql> show grants;
查看当前用户授权
+----------------------------------------------------------------------------------------------------------------------------------------+
| Grants for root@localhost |
+----------------------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY PASSWORD '*D3E4F159E61980989348C890870D0E867F5E532B' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+----------------------------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> show grants for user4@'12.19.23.13';
查看指定用户在指定来源的授权 @部分不能少
+-------------------------------------------------------------------------------------------------------------------+
| Grants for [email protected] |
+-------------------------------------------------------------------------------------------------------------------+
|
GRANT USAGE ON *.* TO 'user4'@'12.19.23.13' IDENTIFIED BY PASSWORD '*CF6E1674E36B571CA309370789323C85CFD8ABE08'
|
|
GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user4'@'12.19.23.13'
|
+-------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
复制user4用户到12.19.23.14上，并保持密码权限一致
mysql> GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user4'@'12.19.23.
14
';
分别执行上面[email protected]授权查询中的结果，并改变IP
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT USAGE ON *.* TO 'user4'@'12.19.23.
14
' IDENTIFIED BY PASSWORD '*CF6E1674E36B571CA309370789323C85CFD8ABE08';
Query OK, 0 rows affected (0.00 sec)
mysql> show grants for [email protected];
查询用户user4在12.19.23.14上的授权
+-------------------------------------------------------------------------------------------------------------------+
| Grants for [email protected] |
+-------------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'user4'@'12.19.23.14' IDENTIFIED BY PASSWORD '
*CF6E1674E36B571CA309370789323C85CFD8ABE08
' |
跟上面12.19.23.13保持一致
| GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user4'@'12.19.23.14' |
跟上面12.19.23.13保持一致
+-------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> exit
可以用quit，exit，和ctrl+d 退出mysql
Bye
[root@aliyun ~]#
常用SQL语句(增删改查)
查：
select count(*) from mysql.user;
统计mysql库里user表的行数，对于数据很大的库不推荐用
select * from mysql.db;
查找mysql库里db表的所有项，对于数据很大的库不推荐用
select db from mysql.db;
查找mysql库里db表的db字段（变量）
select db,user from mysql.db;
查找mysql库里db表的db字段和user字段
select * from mysql.db where host like '192.168.%';
模糊查找mysql库里db表中匹配192.168.的字段
增：
insert into db1.t1 values (1, 'abc');
在db1库的t1表里插入值(1,'abc')
改：
update db1.t1 set name='aaa' where id=1;
更新db1库的t1表，将id=1的项目对应的name值改为aaa
update db1.t1 set id=2 where name=’aaa‘;
更新db1库的t1表，将name=aaa的项目对应的id值改为2
删：
truncate table db1.t1;
清空db1库的t1表，且保留t1表
truncate table t1;
清空当前库的t1表，且保留t1表
（注意当前所在库）
drop table db1.t1;
删除db1库里的t1表
drop table t1;
删除当前库里的t1表
（注意当前所在库）
drop database db1;
删除数据库 db1
例：
[root@aliyun ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 15
Server version: 5.6.40 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
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> use db1;
切换到db1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
查：
mysql> select count(*) from mysql.user;
在db1库下，
统计mysql库里user表的行数
+----------+
| count(*) |
+----------+
| 12 |
+----------+
1 row in set (0.00 sec)
mysql> select * from mysql.db;
查看mysql库里db表的所有内容
+----------------+---------+-------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+
| 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 |
| % | db1 | user3 | Y | Y | Y | Y | Y | Y | N | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 172.19.233.133 | db1 | user4 | Y | Y | Y | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N |
| 172.19.233.134 | db1 | user4 | Y | Y | Y | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N |
+----------------+---------+-------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+
5 rows in set (0.00 sec)
mysql> use mysql;
切换到mysql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 create table user\G
查看user表的建表语句
*************************** 1. row ***************************
Table: user
Create Table: CREATE TABLE `user` (
`Host` char(60) COLLATE utf8_bin NOT NULL DEFAULT '',
`User` char(16) COLLATE utf8_bin NOT NULL DEFAULT '',
`Password` char(41) CHARACTER SET latin1 COLLATE latin1_bin NOT NULL DEFAULT '',
`Select_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Insert_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Update_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Delete_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Create_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Drop_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Reload_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Shutdown_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Process_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`File_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Grant_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`References_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Index_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Alter_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Show_db_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Super_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Create_tmp_table_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Lock_tables_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Execute_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Repl_slave_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Repl_client_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Create_view_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Show_view_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Create_routine_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Alter_routine_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Create_user_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Event_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Trigger_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`Create_tablespace_priv` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
`ssl_type` enum('','ANY','X509','SPECIFIED') CHARACTER SET utf8 NOT NULL DEFAULT '',
`ssl_cipher` blob NOT NULL,
`x509_issuer` blob NOT NULL,
`x509_subject` blob NOT NULL,
`max_questions` int(11) unsigned NOT NULL DEFAULT '0',
`max_updates` int(11) unsigned NOT NULL DEFAULT '0',
`max_connections` int(11) unsigned NOT NULL DEFAULT '0',
`max_user_connections` int(11) unsigned NOT NULL DEFAULT '0',
`plugin` char(64) COLLATE utf8_bin DEFAULT 'mysql_native_password',
`authentication_string` text COLLATE utf8_bin,
`password_expired` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N',
PRIMARY KEY (`Host`,`User`)
) ENGINE=
MyISAM
DEFAULT CHARSET=utf8 COLLATE=utf8_bin COMMENT='Users and global privileges'
这里默认的引擎为mysiam，相对于innodb引擎有自动统计的功能
1 row in set (0.00 sec)
mysql> select db from mysql.db
-> ;
查找mysql库里db表中的db字段
+---------+
| db |
+---------+
| db1 |
| test |
| test\_% |
| db1 |
| db1 |
+---------+
5 rows in set (0.00 sec)
mysql> select db,user from mysql.db;
查找mysql库里db表中的db字段和user字段
+---------+-------+
| db | user |
+---------+-------+
| db1 | user3 |
| test | |
| test\_% | |
| db1 | user4 |
| db1 | user4 |
+---------+-------+
5 rows in set (0.00 sec)
mysql> select * from mysql.db where host like '12.19.%';
模糊查询，匹配’12.19.%‘
+----------------+-----+-------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+
| 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 |
+----------------+-----+-------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+
|
12.19.23.13
| db1 | user4 | Y | Y | Y | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N |
|
12.19.23.14
| db1 | user4 | Y | Y | Y | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N |
+----------------+-----+-------+-------------+-------------+-------------+-------------+-------------+-----------+------------+-----------------+------------+------------+-----------------------+------------------+------------------+----------------+---------------------+--------------------+--------------+------------+--------------+
2 rows in set (0.00 sec)
增：
mysql> insert into db1.t1 values (1,'abc');
在db1库的t1表，插入值(1,'abc'),对于字段的操作要加
' '
Query OK, 1 row affected (0.00 sec)
mysql> select * from db1.t1;
查询db1库t1表
+------+------+
| id | name |
+------+------+
|
1
|
abc
|
+------+------+
1 row in set (0.00 sec)
mysql> insert into db1.t1 values (
2,'123'
);
在db1库的t1表，插入值(2,'123'),对于数字的操作可不加
' '
Query OK, 1 row affected (0.00 sec)
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
|
2
|
123
|
+------+------+
2 rows in set (0.00 sec)
mysql> insert into db1.t1 values (2,'123');
再次插入同样的值
Query OK, 1 row affected (0.01 sec)
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
| 2 | 123 |
| 2 | 123 |
可以通过条件限制雷同，报冲突
+------+------+
3 rows in set (0.00 sec)
mysql> insert into db1.t1 values (2,'234');
再次插入相同的值（id和name）
Query OK, 1 row affected (0.00 sec)
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
| 2 | 123 |
| 2 | 123 |
| 2 | 234 |
+------+------+
4 rows in set (0.00 sec)
改：
mysql> update db1.t1 set name='aaa' where id=2;
更新db1库的t1表，将id=2项目对应的name值改为aaa
Query OK, 3 rows affected (0.00 sec)
Rows matched: 3 Changed: 3 Warnings: 0
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
| 2 | aaa |
| 2 | aaa |
| 2 | aaa |
+------+------+
4 rows in set (0.00 sec)
mysql> update db1.t1 set id=1 where name='aaa';
更新db1库的t1表，将name=aaa的项目对应的id修改为1
Query OK, 3 rows affected (0.00 sec)
Rows matched: 3 Changed: 3 Warnings: 0
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
| 1 | aaa |
| 1 | aaa |
| 1 | aaa |
+------+------+
4 rows in set (0.00 sec)
删：
mysql> delete from db1.t1 where id=1;
删除db1库里t1表中，id=1的项目
Query OK, 4 rows affected (0.00 sec)
mysql> select * from db1.t1;
Empty set (0.00 sec)
已经全部删除了
mysql> insert into db1.t1 values (2,'234');
重新插入值
Query OK, 1 row affected (0.00 sec)
mysql> insert into db1.t1 values (1,'abc');
重新插入值
Query OK, 1 row affected (0.00 sec)
mysql> select * from db1.t1;
查询db1库里t1表的所有项目
+------+------+
| id | name |
+------+------+
| 2 | 234 |
| 1 | abc |
+------+------+
2 rows in set (0.00 sec)
mysql> truncate table db1.t1;
清空db1库里的t1表
Query OK, 0 rows affected (0.05 sec)
mysql> select * from db1.t1;
查询db1库里t1表保存的值
Empty set (0.00 sec)
已经没有值了，为空
mysql> desc db1.t1;
查询db1库里t1表所有的字段
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(4) | YES | | NULL | |
| name | char(40) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> drop table t1;
丢弃当前库里的t1表，会清空表并删除表，
不同于truncate命令
ERROR 1051 (42S02): Unknown table 'mysql.t1'
报错，因为当前所在的是mysql库，没有t1表，
所以请务必小心误删！！！
mysql> drop table db1.t1;
丢弃db1库里的t1表，会清空表并删除表
Query OK, 0 rows affected (0.00 sec)
mysql> desc db1.t1;
查询db1库的t1表，草错，因为表不存在
ERROR 1146 (42S02): Table 'db1.t1' doesn't exist
mysql> drop database db1;
丢弃数据库db1
Query OK, 0 rows affected (0.00 sec)
mysql> show databases;
显示所有数据库
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)
mysql>
MySQL数据库的备份与恢复
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
总结：备份用mysqldump，恢复用mysql，-A 指所有库，-d指建表语句
例：
[root@aliyun ~]# mysqldump -uroot -p123.test mysql
> /tmp/mysqlbak.sql
Warning: Using a password on the command line interface can be insecure.
备份mysql库，不加 > 输出重定向，则只是输出到屏幕上
[root@aliyun ~]# mysql -uroot -p123.test -e "create database mysql2";
Warning: Using a password on the command line interface can be insecure.
创建数据库mysql2
[root@aliyun ~]# mysql -uroot -p123.test mysql2 < /tmp/mysqlbak.sql
Warning: Using a password on the command line interface can be insecure.
恢复备份文件mysqlbak.sql 到mysql2数据库
[root@aliyun ~]# mysql -uroot -p123.test mysql2
进入mysql2数据库
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 19
Server version: 5.6.40 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
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> select database();
查看当前数据库
+------------+
| database() |
+------------+
| mysql2
|
+------------+
1 row in set (0.00 sec)
mysql> show tables;
查看mysql2的所有表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)
mysql> use mysql
切换到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;
查看mysql库里的所有表
+---------------------------+
| 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)
mysql> quit
Bye
[root@aliyun ~]# mysqldump -uroot -p123.test mysql user > /tmp/mysql.user.sql
Warning: Using a password on the command line interface can be insecure.
备份mysql库的user表到/tmp目录下
[root@aliyun ~]# less /tmp/mysql.user.sql
查看备份的表文件mysql.user.sql，找找里边的命令
[root@aliyun ~]# mysql -uroot -p123.test mysql2 < /tmp/mysql.user.sql
Warning: Using a password on the command line interface can be insecure.
恢复备份的表文件mysql.user.sql到mysql2数据库，
不加 表名称 user
[root@aliyun ~]# mysqldump -uroot -p123.test -A > /tmp/mysql_all.sql
Warning: Using a password on the command line interface can be insecure.
备份所有的库到/tmp/目录下
[root@aliyun ~]# mysqldump -uroot -p123.test -d mysql > /tmp/mysql-structure.sql
Warning: Using a password on the command line interface can be insecure.
只
备份mysql库的建表语句（结构），到/tmp/目录下，
没有数据