> mysql安装5.7，确定不是mariadb
* [ ] .rpm -Uvh http://dev.mysql.com/get/mysql-community-release-el6-5.noarch.rpm #下载
* [ ] .yum install yum-utils -y #装源
* [ ] .yum-config-manager --disable mysql56-community # 禁用MySQL5.6的源
* [ ] .yum-config-manager --enable mysql57-community-dmr # 启用MySQL5.7的源
* [ ] .yum repolist enabled | grep mysql
* [ ] .yum install mysql-community-server #安装mysql
>先卸载mariaDb
```
yum remove mariadb
删除配置文件：
rm -f /etc/my.cnf
删除数据目录：
rm -rf /var/lib/mysql/
```
>可能会报错的地方
1. mysql-community-server-5.7.20-1.el6.x86_64 (mysql57-community)需要libsasl2.so.2()(64bit)
* 解决方法
修改 源文件（vim /etc/yum.repos.d/mysql-community.repo）：
```
[mysql57-community]
name=MySQL 5.7 Community Server
## baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/6/$basearch/
##修改这里
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/$basearch/
enabled=1
##修改这里：
gpgcheck=0
##修改这里：
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
```
2.旧的安装包和现在的冲突
```
Transaction check error:
file /usr/share/mysql/charsets/Index.xml from install of mysql-community-common-5.7.27-1.el7.x86_64 conflicts with file from package MariaDB-common-10.2.18-1.el7.centos.x86_64
```
* 解决方法（删除旧的安装包）
rpm -e MariaDB-common-10.2.18-1.el7.centos.x86_64 --nodeps
>安装
yum install mysql-community-server
>启动
```
systemctl start mysqld #启动mysql
systemctl status mysqld #查看mysql启动状态
```
>修改密码
1. 查询初始密码（grep 'temporary password' /var/log/mysqld.log ）
2. mysql -uroot -p
3. 输入刚才查询的初始密码
4. 设置密码校验关闭和密码长度设置允许为0
~~~
set global validate_password_policy=0;
set global validate_password_length=0;
~~~
5. 修改初始密码（SET PASSWORD = PASSWORD('abc1233');）
6. 如果要修改密码为空，必须要关掉密码校验,否则会出现
**Your password does not satisfy the current policy requirements**
7. 降低密码校验长度，密码校验长度由多个值组成，需要全部设置为0
```
SHOW VARIABLES LIKE 'validate_password%';
```
```
set global validate_password_mixed_case_count=0;
set global validate_password_number_count=0;
set global validate_password_special_char_count=0;
set global validate_password_length=0;
```
这样就可以设置密码为空了
8. 设置密码为空
```
update user set authentication_string=password('') where user='root' and host='localhost';
```
5.7的mysql或者maria字段是password
9. 刷新权限
```
flush privileges;
```
