ASP.NET Core中使用EF Core（MySql）Code First

⒈添加依赖

　　MySql.Data.EntityFrameworkCore

⒉在appsettings.json配置文件中配置数据库连接字符串

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    }
  },
  "ConnectionStrings": {
    "MySqlConnection": "server=localhost;port=3306;database=blog;user=root;password=admin"
  },
  "AllowedHosts": "*"
}

⒊编写数据表实体类及上下文

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace NewDb.Models
{
    public class Blog
    {
        public int BlogId { get; set; }
        public string Url { get; set; }

        public ICollection<Post> Posts { get; set; }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace NewDb.Models
{
    public class Post
    {
        public int PostId { get; set; }
        public string Title { get; set; }
        public string Content { get; set; }

        public int BlogId { get; set; }
        public Blog Blog { get; set; }
    }
}

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace NewDb.Models
{
    public class BloggingDbContext : DbContext
    {
        public BloggingDbContext(DbContextOptions<BloggingDbContext> options) : base(options) { }

        public DbSet<Blog> Blogs { get; set; }
        public DbSet<Post> Posts { get; set; }
    }
}

⒋使用依赖注入将上下文注册为服务

        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CookiePolicyOptions>(options =>
            {
                // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                options.CheckConsentNeeded = context => true;
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });


            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

            var connection = Configuration["ConnectionStrings:MySqlConnection"];

            services.AddDbContext<BloggingDbContext>(options =>
            {
                options.UseMySQL(connection);
            });
        }

⒌使用迁移创建数据库

　　第一种方式："Visual Studio 2019" >“工具”>“NuGet 包管理器”>“程序包管理器控制台”，执行以下命令

Add-Migration InitialCreate -v #搭建迁移基架，以便为模型创建一组初始表
Update-Database -v #创建数据库并向其应用新的迁移

　　第二种方式：使用.Net Core CLI，执行以下命令

dotnet ef migrations add InitialCreate -v #搭建迁移基架，以便为模型创建一组初始表
dotnet ef database update -v #创建数据库并向其应用新的迁移