Centos安装mysql 5.7

本文安装的mysql版本为5.7，需要安装mysql 8.0以上可自行换yum文件

### 1、下载和安装mysql

```mysql
yum -y install https://repo.mysql.com//mysql57-community-release-el7-11.noarch.rpm

sed   -i  's/gpgcheck=1/gpgcheck=0/g'   /etc/yum.repos.d/mysql-community.repo
 
 yum clean all 
 
 yum -y install mysql-community-server  mysql-community-client
 ```
 
### 2、配置mysql

vi /etc/my.cnf
	
添加如下内容：
```txt
[mysqld]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
character-set-server =  utf8
collation-server = utf8_general_ci
init_connect =  "SET NAMES 'utf8'"
explicit_defaults_for_timestamp=true
[mysql]
default-character-set  = utf8

[client]
default-character-set  = utf8]
```
### 3、初始化mysql登录密码

```shell
mkdir -p /opt/data/mysql

mysqld --initialize --datadir=/opt/data/mysql --user=mysql

cat /var/log/mysqld.log | grep "temporary password"
```
2023-06-23T14:24:36.418927Z 1 [Note] A temporary password is generated for root@localhost: j_urk/?#t6:Q

j_urk/?#t6:Q就是初始化登录mysql密码

### 4、启动mysql

```shell

# 启动mysql
systemctl  start mysqld

# mysl开机启动
systemctl  enable  mysqld

# 查看mysql启动状态
systemctl status  mysqld
```

### 5、修改密码

登录mysql

mysql -u root -p

修改密码

ALTER USER USER() IDENTIFIED BY 'Admin2023!';

修改成安全级别的密码，例如123456

修改密码策略

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             | LOW   |
| validate_password_special_char_count | 1     |
+--------------------------------------+-------+

```shell
# 密码级别设为低
set global validate_password_policy=LOW;
# 密码最小长度设置为6
set global validate_password_length = 6;
#修改密码为123456
alter user 'root'@'localhost' identified by '123456';
#允许root用户能远程登录
grant all privileges on *.* to root@'%' identified by '123456';
#刷新
FLUSH PRIVILEGES;
```