mysql8.0.21在ubuntu20.04下的配置问题

一、安装命令

sudo apt install mysql-server
# 查看mysql安装状态
sudo service mysql status

二、配置文件的问题

1、配置文件的位置： /etc/mysql

debian.cnf: 保存着账号信息
my.cnf: 指出实际配置文件的位置：/etc/mysql/mysql.conf.d/

mysqld.cnf: 实际的配置信息

2、其他文件位置

/usr/bin                 客户端程序和脚本  
/usr/sbin                mysqld 服务器  
/var/lib/mysql           日志文件，数据库  ［重点要知道这个］  
/usr/share/doc/packages  文档  
/usr/include/mysql       包含( 头) 文件  
/usr/lib/mysql           库  
/usr/share/mysql         错误消息和字符集文件  
/usr/share/sql-bench     基准程序  

三、初始密码的问题

１、root用户的状态

２、更改root用户的密码

在更改密码的同时，还修改user表中的plugin字段为‘mysql_native_password’，该字段的作用还不太明了，看官网说明，大概是密码的验证方式之类的。但不改这个直接修改密码好像还不成功。

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'yourpassword';

3、新添加用户并授权

create user 'admin'@'%' identified by '123';
grant all on * to 'admin'@'%' with grant option;
alter user 'admin'@'%' identified with mysql_native_password by '456';

四、msyqlclient的安装问题

• mysqlclient安装不成功主要缺少两个包：

sudo  apt-get install libmysqlclient-dev libpython3.8-dev

• 如果还有错，那就把wheel装上：

pip install wheel

五、卸载的问题

Removing MySQL with APT

• To uninstall the MySQL server and the related components that have been installed using the MySQL APT repository, first, remove the MySQL server using the following command:

shell> sudo apt-get remove mysql-server

• Then, remove any other software that was installed automatically with the MySQL server:

shell> sudo apt-get autoremove

• To uninstall other components, use the following command, replacing package-name with the name of the package of the component you want to remove:

shell> sudo apt-get remove package-name

• To see a list of packages you have installed from the MySQL APT repository, use the following command:

shell> dpkg -l | grep mysql | grep ii

六、遇到的坑

mysql> show tables;
ERROR 1449 (HY000): The user specified as a definer ('mysql.infoschema'@'localhost') does not exist
mysql> show databases;
ERROR 1449 (HY000): The user specified as a definer ('mysql.infoschema'@'localhost') does not exist

• 第一步，停止MySql服务

service mysql stop

• 第二步，用mysqld对MySql的一些文件进行升级

sudo mysqld --upgrade=FORCE