.NET Core Mysql EF Core中通过dotnet命令Code First创建生成数据库

1､为此示例创建一个控制台应用程序

1) 使用.NET Core命令行界面（CLI）初始化有效的.NET Core项目和控制台应用程序，然后切换到新创建的文件夹（mysqlefcore）

dotnet new console –o mysqlefcore
cd mysqlefcore

2) MySql.Data.EntityFrameworkCore 使用CLI 将包添加到应用程序

dotnet add package MySql.Data.EntityFrameworkCore --version 6.10.8

或者，您可以使用Visual Studio中的程序包管理器控制台添加程序包:

Install-Package MySql.Data.EntityFrameworkCore -Version 6.10.8

注意
版本（例如6.10.8）必须与您使用的实际Connector / NET版本匹配。有关当前版本信息，请参阅 表9.2“支持的Entity Framework Core版本”。

3) 恢复项目文件中指定的依赖项和项目特定工具

dotnet restore

2､创建模型并运行应用程序

控制器应用程序将使用此EF Core示例中的模型。它由两个与书库相关的实体组成，这些实体将在 LibraryContext类（或数据库上下文）中配置。

1) 创建一个名为的新文件LibraryModel.cs ，然后将以下Book和 Publisher类添加到 mysqlefcore命名空间

namespace mysqlefcore
{
  public class Book
  {
    public string ISBN { get; set; }
    public string Title { get; set; }
    public string Author { get; set; }
    public string Language { get; set; }   
    public int Pages { get; set; }
    public virtual Publisher Publisher { get; set; }
  }
  public class Publisher
  {
    public int ID { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Book> Books { get; set; }
  }
}

2) 创建一个名为的新文件LibraryContext.cs并添加后面的代码。将通用连接字符串替换为适合MySQL服务器配置的字符串

该LibraryContext class 实体使用，它使模型的特定属性，如Key，所需的列，引用等的配置。

using Microsoft.EntityFrameworkCore;
using MySQL.Data.EntityFrameworkCore.Extensions;
namespace mysqlefcore
{
  public class LibraryContext : DbContext
  {
    public DbSet<Book> Book { get; set; }
    public DbSet<Publisher> Publisher { get; set; }
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
      optionsBuilder.UseMySQL("server=localhost;database=library;user=user;password=password");
    }
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
      base.OnModelCreating(modelBuilder);
      modelBuilder.Entity<Publisher>(entity =>
      {
        entity.HasKey(e => e.ID);
        entity.Property(e => e.Name).IsRequired();
      });
      modelBuilder.Entity<Book>(entity =>
      {
        entity.HasKey(e => e.ISBN);
        entity.Property(e => e.Title).IsRequired();
        entity.HasOne(d => d.Publisher)
          .WithMany(p => p.Books);
      });
    }
  }
}

3) 将以下代码插入现有 Program.cs文件，替换默认的C＃代码

using Microsoft.EntityFrameworkCore;
using System;
using System.Text;
namespace mysqlefcore
{
  class Program
  {
    static void Main(string[] args)
    {
      InsertData();
      PrintData();
    }
    private static void InsertData()
    {
      using(var context = new LibraryContext())
      {
        // Creates the database if not exists
        context.Database.EnsureCreated();
        // Adds a publisher
        var publisher = new Publisher
        {
          Name = "Mariner Books"
        };
        context.Publisher.Add(publisher);
        // Adds some books
        context.Book.Add(new Book
        {
          ISBN = "978-0544003415",
          Title = "The Lord of the Rings",
          Author = "J.R.R. Tolkien",
          Language = "English",
          Pages = 1216,
          Publisher = publisher
        });
        context.Book.Add(new Book
        {
          ISBN = "978-0547247762",
          Title = "The Sealed Letter",
          Author = "Emma Donoghue",
          Language = "English",
          Pages = 416,
          Publisher = publisher
        });
        // Saves changes
        context.SaveChanges();
      }
    }
    private static void PrintData()
    {
      // Gets and prints all books in database
      using (var context = new LibraryContext())
      {
        var books = context.Book
          .Include(p => p.Publisher);
        foreach(var book in books)
        {
          var data = new StringBuilder();
          data.AppendLine($"ISBN: {book.ISBN}");
          data.AppendLine($"Title: {book.Title}");
          data.AppendLine($"Publisher: {book.Publisher.Name}");
          Console.WriteLine(data.ToString());
        }
      }
    }
  }
}

4) 使用以下CLI命令还原依赖项，然后运行该应用程序

dotnet restore
dotnet run

运行应用程序的输出：

ISBN: 978-0544003415
Title: The Lord of the Rings
Publisher: Mariner Books
ISBN: 978-0547247762
Title: The Sealed Letter
Publisher: Mariner Books

参考文档：https://dev.mysql.com/doc/connector-net/en/connector-net-entityframework-core-example.html