mysql案例

#  安装指定Mysql 版本

## 需要的文件

[RPM-GPG-KEY-mysql-2022](RPM-GPG-KEY-mysql-2022)  

[mysql80-community-release-el7-6.noarch.rpm](mysql80-community-release-el7-6.noarch.rpm) 

## 上传到centos服务器

```bash
scp D:\ResilioSync\文档\MYSQL\mysql80-community-release-el7-6.noarch.rpm D:\ResilioSync\文档\MYSQL\RPM-GPG-KEY-mysql-2022 root@116.63.51.40:~
```


## 安装 rmp 和 GpG密钥

```bash
ls
yum install mysql80-community-release-el7-6.noarch.rpm -y
rpm --import RPM-GPG-KEY-mysql-2022
```



## 使用 yum-utils 管理扩展包

```bash
yum install yum-utils -y
```


## 修改MySQL默认安装版本

```bash
yum-config-manager --disable mysql80-community
yum-config-manager --enable mysql57-community
```



## 安装mysql 5.7

```bash
yum install mysql-community-server -y
```


# 启动&&配置

## 启动

```bash
systemctl start mysqld
systemctl enable mysqld
```


## 查看默认密码

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


## 修改默认密码

```bash
mysql -uroot -p

```

```sql
ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass4!';
FLUSH PRIVILEGES;

```


## 创建远程连接用户

```sql
CREATE USER 'username'@'%' IDENTIFIED BY 'Password1!';
FLUSH PRIVILEGES;
```


## 用户授权所有数据库所有权限

```sql
 GRANT ALL ON *.* TO 'username'@'%';
 FLUSH PRIVILEGES;
```


## 修改用户密码

```sql
SET PASSWORD FOR 'username'@'%' = PASSWORD('newpassword');
FLUSH PRIVILEGES;
```

## 修改密码策略

### 查看当前策略

```sql
show VARIABLES like "%password%";
```



### 修改策略和密码长度

```sql
set global validate_password_policy=0;
set global validate_password_length=5;
FLUSH PRIVILEGES;
```