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