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

⒈創建數據庫，在數據中執行以下腳本。

CREATE DATABASE Blogging;

USE Blogging;

CREATE TABLE Blog (
    BlogId int not null PRIMARY key auto_increment,
    Url text not null
);

CREATE TABLE Post (
    PostId int NOT NULL PRIMARY key auto_increment,
    BlogId int NOT NULL,
    Content text,
    Title varchar(100),
    CONSTRAINT FK_Post_Blog_BlogId FOREIGN KEY(BlogId) REFERENCES Blog(BlogId) ON DELETE CASCADE
);

INSERT INTO Blog (Url) VALUES
('http://blogs.msdn.com/dotnet'),
('http://blogs.msdn.com/webdev'),
('http://blogs.msdn.com/visualstudio')

⒉添加依賴

　　MySql.Data.EntityFrameworkCore

⒊實施反向工程，基於現有數據庫創建數據表實體類及上下文。

　　第一種方式："Visual Studio 2019" >“工具”>“NuGet 包管理器”>“程序包管理器控制台”，執行以下命令(最好提前編譯以下項目，否則以下命令可能執行不成功)

#Scaffold-DbContext "數據庫連接字符串" 數據庫提供程序 -OutputDir 輸出文件夾
Scaffold-DbContext "server=localhost;port=3306;database=blogging;user=root;password=admin;" MySql.Data.EntityFrameworkCore -OutputDir Models

　　第二種方式：使用.Net Core CLI，執行以下命令

#dotnet ef dbcontext scaffold "數據庫連接字符串" 數據庫提供程序 -o 輸出文件夾
dotnet ef dbcontext scaffold "server=localhost;port=3306;database=blogging;user=root;password=admin;" MySql.Data.EntityFrameworkCore -o Models

⒋使用依賴注入將上下文注冊為服務

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);
            });
        }