安装迁移工具需要的插件

• Microsoft.EntityFrameworkCore.Tools
• Microsoft.EntityFrameworkCore.Design

补充说明：
安装在Demo.Data项目下，很显然这里需要迁移的是DbContext，与此同时，安装了Microsoft.EntityFrameworkCore,Tools就会依赖另一个，所以无需安装另一个。

迁移命令

1. 搜索框输入：Package Manager Console
2. Default Project选择Demo.Data
3. 键入：get-help entityFramework 出现独角兽

1. 开始迁移，即将三个model嵌入到数据库中：Add-Migration Initial

1. 需要对Demo.App安装Microsoft.EntityFrameworkCore.Design

1. 再次使用add-migration Initial

1. 清空指令 clear
2. 生成数据库的脚本Script-Migration ```sql IF OBJECT_ID(N’[EFMigrationsHistory]’) IS NULL BEGIN CREATE TABLE [EFMigrationsHistory] (

    [MigrationId] nvarchar(150) NOT NULL,
    [ProductVersion] nvarchar(32) NOT NULL,
    CONSTRAINT [PK___EFMigrationsHistory] PRIMARY KEY ([MigrationId])

   ); END;

GO

CREATE TABLE [Leagues] ( [Id] int NOT NULL IDENTITY, [Name] nvarchar(max) NULL, [Country] nvarchar(max) NULL, CONSTRAINT [PK_Leagues] PRIMARY KEY ([Id]) );

GO

CREATE TABLE [Clubs] ( [Id] int NOT NULL IDENTITY, [Name] nvarchar(max) NULL, [City] nvarchar(max) NULL, [DateOfEstablishment] datetime2 NOT NULL, [History] nvarchar(max) NULL, [LeagueId] int NULL, CONSTRAINT [PK_Clubs] PRIMARY KEY ([Id]), CONSTRAINT [FK_Clubs_Leagues_LeagueId] FOREIGN KEY ([LeagueId]) REFERENCES [Leagues] ([Id]) ON DELETE NO ACTION );

GO

CREATE TABLE [Players] ( [Id] int NOT NULL IDENTITY, [Name] nvarchar(max) NULL, [DateOfBirth] datetime2 NOT NULL, [ClubId] int NULL, CONSTRAINT [PK_Players] PRIMARY KEY ([Id]), CONSTRAINT [FK_Players_Clubs_ClubId] FOREIGN KEY ([ClubId]) REFERENCES [Clubs] ([Id]) ON DELETE NO ACTION );

GO

CREATE INDEX [IX_Clubs_LeagueId] ON [Clubs] ([LeagueId]);

GO

CREATE INDEX [IX_Players_ClubId] ON [Players] ([ClubId]);

GO

INSERT INTO [__EFMigrationsHistory] ([MigrationId], [ProductVersion]) VALUES (N’20200828130407_Initial’, N’3.1.7’);

GO

```

1. 开发环境我们使用Update-Database -verbose(生成log明细)
2. 这里提一个概念，反向工程，即数据已经存在表了