5、安装MySql

• 配置安装YUM源

# 在http://dev.mysql.com/downloads/repo/yum/找到对应的版本并下载
# 如：https://repo.mysql.com//mysql57-community-release-el7-10.noarch.rpm

# 安装源
yum localinstall mysql57-community-release-el7-8.noarch.rpm

• 安装

yum install mysql-community-server

• 启动

systemctl start mysqld

• 设置开机启动

systemctl enable mysqld
systemctl daemon-reload

• 查看root用户原始密码

grep 'temporary password' /var/log/mysqld.log

• 登录MySql，并修改root用户密码

mysql -uroot -p

# 在MySql命令行下
mysql> set password for 'root'@'localhost'=password('NewPass1!'); 

• 退出MySql命令行

mysql> exit

• 重启MySql

systemctl restart mysqld

• 附：修改默认编码为utf-8

# 在MySql命令行下
# 查看编码
mysql> show variables like '%character%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | latin1                     |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | latin1                     |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

# 修改/etc/my.cnf配置文件，在[mysqld]下添加编码配置，如下所示：
[mysqld]
character_set_server=utf8
init_connect='SET NAMES utf8'

# 重启MySql，再次查看编码
mysql> show variables like '%character%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | utf8                       |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8                       |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

• 附：修改密码策略，使之可以使用简易密码

# 在MySql命令行下
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      |
+--------------------------------------+--------+

mysql> SET GLOBAL validate_password_length = 3;
mysql> SET GLOBAL validate_password_number_count = 0;
mysql> SET GLOBAL validate_password_mixed_case_count = 0;
mysql> SET GLOBAL validate_password_special_char_count = 0;

# 然后就可以修改简易密码了
mysql> set password for 'root'@'localhost'=password('root'); 

• 附：开启root用户远程登陆

mysql> use mysql;
Database changed
mysql> grant all privileges  on *.* to root@'%' identified by "root";
Query OK, 0 rows affected (0.00 sec)

update user set host='%' where user ='root';
flush privileges;