前提你的mysql是通过yum安装，其他情况没有测试
检查是否是 yum安装的mysql
yum list installed | grep mysql
删除通过yum安装的 MySQL
yum -y remove mysql-libs.x86_64 yum -y remove mysql-*
更新yum源
以下 mysql-community-release-el6-5.noarch.rpm 镜像源根据实际情况下载 查看yum源
代码语言：javascript复制# 下载镜像源
wget dev.mysql.com/get/mysql-community-release-el6-5.noarch.rpm
# 本地配置镜像源
yum localinstall mysql-community-release-el6-5.noarch.rpm
# 查看本地镜像源是否生效
yum repolist all | grep mysql看到的应该是这样的
代码语言：javascript复制mysql-connectors-community/x86_64 MySQL Connectors Community 启用: 30
mysql-connectors-community-source MySQL Connectors Community - Sourc 禁用
mysql-tools-community/x86_64 MySQL Tools Community 启用: 40
mysql-tools-community-source MySQL Tools Community - Source 禁用
mysql55-community/x86_64 MySQL 5.5 Community Server 禁用
mysql55-community-source MySQL 5.5 Community Server - Sourc 禁用
mysql56-community/x86_64 MySQL 5.6 Community Server 禁用
mysql56-community-source MySQL 5.6 Community Server - Sourc 禁用
mysql57-community-dmr/x86_64 MySQL 5.7 Community Server Develop 启用: 164
mysql57-community-dmr-source MySQL 5.7 Community Server Develop 禁用# 禁用 MySQL 5.5和5.6的源
yum-config-manager --disable mysql55-community
yum-config-manager --disable mysql56-community
# 启用 MySQL 5.7的源
yum-config-manager --enable mysql57-community-dmr
# 查看是否生效
yum repolist enabled | grep mysql看到的应该是这样的
代码语言：javascript复制mysql-connectors-community/x86_64 MySQL Connectors Community 30
mysql-tools-community/x86_64 MySQL Tools Community 40
mysql57-community-dmr/x86_64 MySQL 5.7 Community Server Development M 164安装 MySQL server
代码语言：javascript复制# 安装
yum install mysql-community-server
# 启动
service mysqld start到这里时有些会报一下错
代码语言：javascript复制错误显示：
软件包：mysql-community-server-5.7.20-1.el6.x86_64 (mysql57-community)
需要：libsasl2.so.2()(64bit)
您可以尝试添加 --skip-broken 选项来解决该问题
您可以尝试执行：rpm -Va --nofiles --nodigest解决方法：
代码语言：javascript复制修改vim /etc/yum.repos.d/mysql-community.repo 源文件
[mysql57-community]
name=MySQL 5.7 Community Server更换目的yum源地址
代码语言：javascript复制## baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/6/$basearch/
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/$basearch/
enabled=1
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql yum install mysql-community-server #再次安装mysql
安装完成，更新相关配置
不出意外你的mysql应该是没法登录的
代码语言：javascript复制# 停掉 mysql
service mysqld stop
# 启动安全模式
mysqld_safe --skip-grant-tables
# 在新的终端登录mysql
mysql在mysql命令行下修改密码
代码语言：javascript复制# 切换数据库
mysql> use mysql;
# 更新密码
mysql> UPDATE user SET authentication_string=PASSWORD('新密码') WHERE User='root';
# 刷新权限
mysql> flush privileges;
# 退出登录
mysql> exit;重新启动mysql service mysqld start
如果在以上几步之后依然无法登录，并且提示：Table 'performance_schema.session_variables' doesn't exist 错误,你可以更新mysql结构,然后重复以上Step4步骤即可，操作如下
mysql_upgrade -u root -p --force
