使用EF操作Docker中的Mysql实例

　　为啥我会选择mysql呢？因为我的服务器配置较低，而SqlServer在docker中的实例，服务器的运行内存应当保持在2G+,我没有这个条件,它会爆出这样的错误 sqlservr: This program requires a machine with at least 2000 megabytes of memory. 听我朋友说就算你的机器是2G的，也会报这个错误，看了好多网上破解的很是不友好，害怕出更多的问题，所以自然就选择了MySql，（SqlServer吃配置还是很高的）...　　

　　当然我们首先也应当在docker中安装mysql容器，我们首先可以通过 docker search mysql 来查询关键字的镜像。NAME:镜像仓库源的名称、DESCRIPTION:镜像的描述、OFFICIAL:是否docker官方发布..如果要看实际的version，则就可以去https://hub.docker.com/ 中找找了.

[root@iZenarrdqnvpc4Z ~]# docker search mysql
NAME                              DESCRIPTION                                     STARS               OFFICIAL            AUTOMATED
mysql                             MySQL is a widely used, open-source relation…   8995                [OK]                
mariadb                           MariaDB is a community-developed fork of MyS…   3175                [OK]                
mysql/mysql-server                Optimized MySQL Server Docker images. Create…   669                                     [OK]
percona                           Percona Server is a fork of the MySQL relati…   464                 [OK]                
centos/mysql-57-centos7           MySQL 5.7 SQL database server                   66                                      
centurylink/mysql                 Image containing mysql. Optimized to be link…   61                                      [OK]
mysql/mysql-cluster               Experimental MySQL Cluster Docker images. Cr…   59                                      
deitch/mysql-backup               REPLACED! Please use http://hub.docker.com/r…   41                                      [OK]

下面直接安装mysql镜像，通过命令 docker pull mysql:latest  ，装了个最新版的..哈哈 喜新厌旧嘛...出现了status就ok了...

[root@iZenarrdqnvpc4Z ~]# docker pull mysql:latest 
latest: Pulling from library/mysql
804555ee0376: Pull complete 
c53bab458734: Pull complete 
ca9d72777f90: Pull complete 
2d7aad6cb96e: Pull complete 
...............................
Digest: sha256:e1b0fd480a11e5c37425a2591b6fbd32af886bfc6d6f404bd362be5e50a2e632
Status: Downloaded newer image for mysql:latest
docker.io/library/mysql:latest

随后创建Mysql挂在目录，用于存放配置、数据、日志文件，随后启动mysql容器并指定刚刚创建的挂在目录，这两行是分开执行的。

mkdir -p $HOME/mysql/{conf.d,data,logs}
docker run --name mysql -p 3306:3306 -v $HOME/mysql/data:/var/lib/mysql -v $HOME/mysql/conf.d:/etc/mysql/conf.d -v $HOME/mysql/logs:/logs --privileged=true -e MYSQL_ROOT_PASSWORD=123456 -d mysql

进入mysql容器。通过root账号登录mysql服务，然后它让你输入密码，这个场景下应该是123456，如果没问题的话就进去了mysql开头的tag中。

[root@iZenarrdqnvpc4Z ~]# docker exec -it mysql /bin/bash
root@7b96a24b92c2:/# mysql -u root -p #{123456}
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or g.
Your MySQL connection id is 14
Server version: 8.0.18 MySQL Community Server - GPL

Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type "help;" or "h" for help. Type "c" to clear the current input statement.
mysql> 

如果想要修改root密码的话，直接把root密码置空随后修改密码。

# 把root密码置空 
update user set authentication_string = "" where user = "root" and host = "localhost";
# 修改root密码
alter user root@"localhost" identified by "你的密码";

如果你要添加用户给别人用，则可以这么做。

# 添加用户
create user dev@"%" identified by "123456";
# 给用户授权
grant Alter, Create, Create Temporary Tables, Create User, Create View, Delete, Drop, Event, Index, Insert, Lock Tables, Process, References, Reload, Select, Show Databases, Show View, Trigger, Update on *.* to dev@"%";
# 刷新权限
flush privileges; 

完事之后你就可以通过navticat premium 工具进行远程连接了...

随后我们创建一个.NET Core工程，添加EF关于MySql的相关包，这里我遇到了一个问题，在我使用 MySql.Data.EntityFrameworkCore 实体移植的时候爆出下面的错误，目前还不知道是什么原因。在.NET Core 3.0+ 有BUG吧。回头我去提交个issues ...

System.TypeLoadException: Method "get_Info" in type "MySql.Data.EntityFrameworkCore.Infraestructure.MySQLOptionsExtension" from assembly "MySql.Data.EntityFrameworkCore, Version=8.0.18.0, Culture=neutral, 

所以我使用了 pomelo作为代替它，发现毫无异常。直接code first 开干。

public class MysqlDbContext : DbContext
    {
        public DbSet students { get; set; }
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            //base.OnConfiguring(optionsBuilder);
            string sqlConnection = "server=IP;uid=zaranet;pwd=123456;database=MyDemo";
            optionsBuilder.UseMySql(sqlConnection);
        }
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
        }          
    }

随后直接 Add-Migration Init ，再update..

PM> Add-Migration Init
To undo this action, use Remove-Migration.
PM> update-database Init

OK,打开navicat 看一下 成功了。