实体框架5为表指定了多个标识列。每个表只允许一个标识列

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问题描述

我正在创建此模型作为我的代码优先实体框架的一部分

I am creating this model as part of my code first entity framework

public class NewUserRegistration
{
    [Key]
    public int NewUserRegistrationId { get; set; }
}

使用 Update-Database -Verbose -Force软件包管理器控制台中的命令我在更新的这一点得到此异常应用自动迁移：201211252223088_AutomaticMigration。

Using the Update-Database -Verbose -Force command in the Package Manger ConsoleI get this exception during the this bit of the update Applying automatic migration: 201211252223088_AutomaticMigration.

很明显，只指定了一个标识列。那么为什么会这样呢？

There is plainly only one Identity Column specified. So why is this the case?

这样做的时候我也不会例外。

When I do this I get no exception.

public class NewUserRegistration
{
    [Key]
    public int Id { get; set; }
}

有人对为什么会这样吗？

Any thoughts on why this is the case?

EDIT

我应该说我正在更改键。评论说您不能只是这样做。如何删除并重新创建？

I should say that I am changing the name of the key. The comments say that you can't just do this. How can I drop and recreate?

是否最好从SQL中删除数据库，然后再次运行 Update-Database 命令？

Is it best to delete the database from SQL and then just run the Update-Database command again?

推荐答案

尝试重命名Key列时遇到相同的错误。为了使迁移工作正常进行，我必须在脚手架迁移脚本中重新排序操作的顺序。

I encountered the same error when trying to rename a Key column. To make the migration work, I had to reorder the order of operations in my scaffolded migration script.

在这里，我确保先对Drop操作进行排序，然后添加

Here, I made sure to order the Drop operations first, then added the new Key field afterwards.

public partial class RenameKey : DbMigration
{
    public override void Up()
    {
        DropPrimaryKey("dbo.GameSummary", new[] { "OldId" });
        DropColumn("dbo.GameSummary", "OldId");
        AddColumn("dbo.GameSummary", "Id", c => c.Int(nullable: false, identity: true));
        AddPrimaryKey("dbo.GameSummary", "Id");
    }

希望对您的案件有所帮助。

Hope that helps with your case.

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