1、新版 MySQL 权限问题：

问题：SQL Error (1130): Host '192.168.1.100' is not allowed to connect to this MySQL server 说明所连接的用户帐号没有远程连接的权限，只能在本机(localhost)登录。需更改 mysql 数据库里的 user表里的 host项：把localhost改称% mysql>use mysql; mysql>update user set host = '%' where user ='root'; mysql>flush privileges; mysql>select 'host','user' from user where user='root'; 旧版本 MySQL 可以 IP 授权与修改密码同时进行： GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '123456' WITH GRANT OPTION; 注意0：授权可以用上述语句，但是修改密码新版 MySQL 不能再用 WITH GRANT OPTION 了：Using GRANT statement to modify existing user properties other than privileges is deprecated and will be removed in future release. Use ALTER USER statement for this operation. ALTER USER 'root'@'%' IDENTIFIED BY 'pwd';

注意1：MySQL 用户权限标示是 user 和 host 组成的二元组，上述语句需要确保该二元组存在，否则会报错：

mysql> ALTER USER 'root'@'%' IDENTIFIED BY 'pwd'; ERROR 1396 (HY000): Operation ALTER USER failed for 'root'@'%' mysql> create user 'root'@'%' identified by 'pwd'; Query OK, 0 rows affected (0.00 sec)

mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION; Query OK, 0 rows affected (0.00 sec)

mysql> show grants for current_user(); +---------------------------------------------------------------------+ | Grants for root@localhost | +---------------------------------------------------------------------+ | GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION | | GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION | +---------------------------------------------------------------------+ 2 rows in set (0.00 sec) 如果使用 ALTER USER 'root'@'%' IDENTIFIED WITH sha256_password BY 'pwd'; 指定加密方式则可能在客户端连接时有问题：注意2：ERROR 2059 (HY000): Authentication plugin 'sha256_password' cannot be loaded: No such file or directory update user set plugin='mysql_native_password' where user = 'root' and host = '%'; update mysql.user set password=PASSWORD("pwd") where User='root'; 注意3：ERROR 1054 (42S22): Unknown column 'password' in 'field list' update mysql.user set authentication_string=password("pwd") where user='root'; 注意4：'PASSWORD' is deprecated and will be removed in a future release. password 即将被废弃，官方不建议用继续使用了，建议使用第1点中的 ALTER USER 语法去管理用户属性。

Access denied for user 'root'@'IP地址' ,是因为相应的主机没有对应的访问权限

--开放权限如下
use mysql;
update user u set u.host = '%' where u.user = 'root' limit 1;
flush privileges;

--查看用户权限
show grants for current_user();

--mysql不推荐通过修改表的方式修改用户密码
INSERT or UPDATE statements for the mysql.user table that refer to literal passwords are logged as is,so you should avoid such statements
--通过客户端sql修改
MariaDB [mysql]>  UPDATE user SET Password = password('123456') WHERE User = 'root' ;
--此时可在binglog中可以看到明文的密码
[root@rudy_01 3306]# mysqlbinlog binlog.000006 --start-position=4224 >/tmp/test.sql
[root@rudy_01 3306]# cat /tmp/test.sql 
SET @@session.collation_database=DEFAULT/*!*/;
UPDATE user SET Password = password('123456') WHERE User = 'root'

--在 mysql 5.7 中 password 字段已经不存在了
mysql> UPDATE user SET Password = password('123456') WHERE User = 'root' ;
ERROR 1054 (42S22): Unknown column 'Password' in 'field list'

mysql> desc user;
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Field                  | Type                              | Null | Key | Default               | Extra |
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Host                   | char(60)                          | NO   | PRI |                       |       |
| User                   | char(32)                          | NO   | PRI |                       |       |
| Select_priv            | enum('N','Y')                     | NO   |     | N                     |       |

--注意出于安全考虑，alter user 时提示更新的是 0 条数据，但实际 password 已更新
mysql> select host,user,authentication_string,password_last_changed from user where user='root' and host='%';
+------+------+-------------------------------------------+-----------------------+
| host | user | authentication_string                     | password_last_changed |
+------+------+-------------------------------------------+-----------------------+
| %    | root | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | 2016-01-08 15:38:13   |
+------+------+-------------------------------------------+-----------------------+
1 row in set (0.04 sec)

--提示更新0条，使用此方法不需要再 flush privileges
If you modify the grant tables indirectly using account-management statements such as GRANT, REVOKE,SET PASSWORD, or RENAME USER, 
the server notices these changes and loads the grant tables into memory again immediately.
mysql>  alter user 'root'@'%' identified by '12345678';
Query OK, 0 rows affected (0.00 sec)
--实际已更新
mysql>  select host,user,authentication_string,password_last_changed from user where user='root' and host='%';
+------+------+-------------------------------------------+-----------------------+
| host | user | authentication_string                     | password_last_changed |
+------+------+-------------------------------------------+-----------------------+
| %    | root | *84AAC12F54AB666ECFC2A83C676908C8BBC381B1 | 2016-01-08 15:53:09   |
+------+------+-------------------------------------------+-----------------------+
1 row in set (0.00 sec)

--在binlog中查出的sql如下
[root@rudy mysql]# cat /tmp/test.sql
SET @@session.collation_database=DEFAULT/*!*/;
ALTER USER 'root'@'%' IDENTIFIED WITH 'mysql_native_password' AS '*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9'


--mysql对于密码有3种检验策略，默认validate_password_policy为MEDIUM
? LOW policy tests password length only. Passwords must be at least 8 characters long.
? MEDIUM policy adds the conditions that passwords must contain at least 1 numeric character, 1 lowercase and uppercase character, and 1 special (nonalphanumeric) character.
? STRONG policy adds the condition that password substrings of length 4 or longer must not match words

--注意validate_password默认是没有安装的
If the validate_password plugin is not installed, the validate_password_xxx system variables are not available, 
passwords in statements are not checked, and VALIDATE_PASSWORD_STRENGTH() always returns 0.
 
 
--检验密码复杂度 
mysql> select VALIDATE_PASSWORD_STRENGTH('abc1235jeme');
+-------------------------------------------+
| VALIDATE_PASSWORD_STRENGTH('abc1235jeme') |
+-------------------------------------------+
|                                         0 |
+-------------------------------------------+
1 row in set (0.00 sec)
--查找安装的插件，发现找不到validate_password
mysql> show plugins;
--手动安装
mysql> INSTALL PLUGIN validate_password SONAME 'validate_password.so';
mysql> show plugins;
+----------------------------+----------+--------------------+----------------------+---------+
| Name                       | Status   | Type               | Library              | License |
+----------------------------+----------+--------------------+----------------------+---------+
| validate_password          | ACTIVE   | VALIDATE PASSWORD  | validate_password.so | GPL     |
+----------------------------+----------+--------------------+----------------------+---------+
45 rows in set (0.04 sec)
--再次检验密码复杂度 
mysql> select VALIDATE_PASSWORD_STRENGTH('abc1235jeme');
+-------------------------------------------+
| VALIDATE_PASSWORD_STRENGTH('abc1235jeme') |
+-------------------------------------------+
|                                        50 |
+-------------------------------------------+

--安装validate_password插件后，就必需符合validate_password_policy的要求，否则语句执行出错
mysql> alter user 'root'@'%' identified by '123456';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

2、主从复制遇到的权限及异常问题

1、主从均需重启mysql服务
/etc/init.d/mysqld restart
或者：
sudo service mysqld restart 

2、主配置：增加从机复制账户并授权，以便从机远程登录过来复制 binlog
create user 'replicationUsername'@'%' identified by 'Passwd';
GRANT REPLICATION SLAVE,RELOAD,SUPER ON *.* TO 'name'@'%'  WITH GRANT OPTION;
show master status;

3、从配置：
stop slave;
CHANGE MASTER TO
  MASTER_HOST='110.126.103.126',
  MASTER_USER='replicationUsername',
  MASTER_PASSWORD='Passwd',
  MASTER_PORT=3306,
  MASTER_LOG_FILE='mysql-bin.000001',
  MASTER_LOG_POS=154,
  MASTER_CONNECT_RETRY=10;
start slave;
show slave statusG

4、Slave_SQL_Running: No
    1.程序可能在slave上进行了写操作
    2.也可能是slave机器重起后，事务回滚造成的.
    3.也可能遇到各种SQL错误导致 SQL 线程中断退出。
    解决方法:
stop slave;
set global sql_slave_skip_counter = 1 ;
start slave;
    之后Slave会和Master去同步 主要看:
从机：show slave statusG
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Seconds_Behind_Master是否为0，0就是已经同步了
主机：show processlistG
如果出现Command: Binlog Dump,则说明配置成功.

5、测试：
create database db_test_slave;  
use db_test_slave;  
create table tb_test(id int(3), name varchar(50));  
insert into tb_test values(1,'hello slave');  
show databases;  

6、slave 从零开始同步 master 所有数据库：
（1）master操作:
RESET MASTER;
FLUSH TABLES WITH READ LOCK;
SHOW MASTER STATUS;

candidates=$(echo "show databases" | mysql -uroot -pPASSWD| grep -Ev "^(Database|sys|mysql|performance_schema|information_schema)$")
mysqldump -uroot -pPASSWD --databases ${candidates} --single-transaction > mysqldump.sql
UNLOCK TABLES;

（2）slave操作:
nc -l 12345 < <(cat mysqldump.sql) ##主
nc -n 10.48.186.32 12345 > mysqldump.sql 

STOP SLAVE;
mysql -uroot -pPASSWD < mysqldump.sql

show master status; --主

CHANGE MASTER TO
  MASTER_HOST='10.48.186.32',
  MASTER_USER='birepl',
  MASTER_PASSWORD='PASSWD',
  MASTER_PORT=3306,
  MASTER_LOG_FILE='mysql-bin.000001',
  MASTER_LOG_POS=398062,
  MASTER_CONNECT_RETRY=10;
RESET SLAVE;
start slave;
SHOW SLAVE STATUSG