安装mysql5.7

 环境： CentOS7

 mysql源选择本地源：

[root@master ~]# ll win-share/mysql/57/
总用量 207346
-rwxrwxrwx. 1 root root  26468960 2月  28 22:17 mysql-community-client-5.7.33-1.el7.x86_64.rpm
-rwxrwxrwx. 1 root root    315280 12月 11 13:20 mysql-community-common-5.7.33-1.el7.x86_64.rpm
-rwxrwxrwx. 1 root root   2458780 12月 11 13:21 mysql-community-libs-5.7.33-1.el7.x86_64.rpm
-rwxrwxrwx. 1 root root   1260364 12月 11 13:21 mysql-community-libs-compat-5.7.33-1.el7.x86_64.rpm
-rwxrwxrwx. 1 root root 181817592 2月  26 16:45 mysql-community-server-5.7.33-1.el7.x86_64.rpm
drwxrwxrwx. 1 root root         0 3月   2 10:36 repodata

安装：

[root@master ~]# yum install mysql-community-server

从log日志里查看mysql的登录密码： ?O:Askd)s9tu就是系统生成的密码

[root@master ~]# grep "temporary password is generated" /var/log/mysqld.log
2021-03-09T23:36:31.157066Z 1 [Note] A temporary password is generated for root@localhost: ?O:Askd)s9tu

登录：因密码中有特殊字符所以要在-p后加“”（双引号）把密码括起来。

[root@master ~]# mysql -uroot -p"?O:Askd)s9tu"
mysql: [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: 5.7.33

Copyright (c) 2000, 2021, Oracle and/or its affiliates.

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> 

　　跳过密码验证:在my.cnf的[mysqld]项里加入skip-grant-tables,并重启mysql生效

[root@CentOS7 ~]# vi + /etc/my.cnf     

[mysqld]
skip-grant-tables

　　

修改密码强度限制：（默认8位、大小写字母、特殊符号、数字）

注意：因为是实验环境密码强度可以降低，如果是生产环境要注意安全。

先修改默认密码：否则什么都不会让你操作

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '?O:Askd)s9tu1';
Query OK, 0 rows affected (0.00 sec)

查看密码规则：

mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+--------+
| Variable_name                        | Value  |
+--------------------------------------+--------+
| validate_password_check_user_name    | OFF    |
| validate_password_dictionary_file    |        |
| validate_password_length             | 8      |
| validate_password_mixed_case_count   | 1      |
| validate_password_number_count       | 1      |
| validate_password_policy             | MEDIUM |
| validate_password_special_char_count | 1      |
+--------------------------------------+--------+
7 rows in set (0.01 sec)

临时,在mysql降低密码强度等级，

 注意:重启数据库此项设置失效,将被还原成默认

mysql>  set global validate_password_policy=LOW; 
Query OK, 0 rows affected (0.00 sec)　

临时,密码长度设为6 默认8 

 注意:重启数据库此项设置失效,将被还原成默认

mysql> set global validate_password_length=6;
Query OK, 0 rows affected (0.01 sec)

永久,不需要密码策略，在/etc/my.cnf文件中添加如下配置,禁用即可

validate_password = off

永久，/etc/my.cnf文件中添加

[root@CentOS7 ~]# vi + /etc/my.cnf     

[mysqld]
validate_password_policy=0     #0（LOW），1（MEDIUM），2（STRONG）

永久,在/et/my.cnf文件中添加。

   注意：如果设置validate_password = off ，validate_password_length 项会失效。

[root@CentOS7 ~]# vi + /etc/my.cnf     

[mysqld]
validate_password_length=6

设置root密码为123456

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '123456'; 
Query OK, 0 rows affected (0.00 sec)

 查看数据库中的用户授权访问列表:

命令"use mysql"进入到mysql数据库中，再使用语句"select host, user from user;"查询登录用户的授权列表 ,显示root用户只能从本能登录.

mysql> use mysql;
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> select host, user from user;
+---------------------+---------------+
| host                | user          |
+---------------------+---------------+
| localhost           | mysql.session |
| localhost           | mysql.sys     |
| localhost           | root          |
+---------------------+---------------+

授权用户远程登录

 注意:密码12345强度根据你mysql系统设置来设定,否则可能失败.

1、授权root用户可以从10.10.1.35登录MySQL数据库，如下所示：

mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'10.10.1.35' IDENTIFIED BY '123456' WITH GRANT OPTION;

2、授权root用户可以从任意电脑登录MySQL数据库。如下所示：

mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '123456' WITH GRANT OPTION;

保存授权名单

mysql> flush privileges;　

 删除授权地址和用户

mysql> delete from user where host = 'host地址' and user = '登录名';

　　

测试数据库是否能正常操作：

mysql>use test;
Database changed

mysql>create table abc.t0417(id int,name varchar(20));
Query OK, 0 rows affected (0.08 sec)

mysql>use test;
Database changed

mysql>insert into abc.t0417 values(1,'a');
Query OK, 1 row affected (0.02 sec)

mysql>select * from t0417;
+------+------+
| id   | name |
+------+------+
|    1 | a    |
+------+------+
1 rows in set (0.01 sec)

　　

　　

 ===========================================================================================================================

 错误: 

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

原因:重启Mysql前没有退出mysql客户端命令行.

解决方法:quit（exit）退出命令行,重新进入.

参考：

http://blog.csdn.net/wohiusdashi/article/details/89358071

http://zhuanlan.zhihu.com/p/200909519

http://jingyan.baidu.com/article/f7ff0bfcb914916e26bb13ac.html

http://moneyslow.com/mysql-5-7-关闭密码策略设置validate_password.html

t0417