为表异常指定的多个标识列 [英] Multiple identity columns specified for table exception

问题描述

我有这个初始迁移：

namespace DataAccess.Migrations
{
    using System.Data.Entity.Migrations;

    public partial class init : DbMigration
    {
        public override void Up()
        {
            CreateTable(
                "dbo.SchoolclassCodes",
                c => new
                    {
                        Schoolclass = c.Int(nullable: false, identity: true),
                        Type = c.String(),
                    })
                .PrimaryKey(t => t.Schoolclass);

        }

        public override void Down()
        {
            DropTable("dbo.SchoolclassCodes");
        }
    }
}

schoolclass属性是数据类型整数和主键。

The schoolclass property is of datatype integer and the primary key.

我已经在schoolclassCode表中填写了数据。

I have already data filled in the schoolclassCode table.

现在我更改了数据类型从整数到字符串，并创建了另一个迁移：

Now I changed the datatype from integer to string and created another migration:

namespace DataAccess.Migrations
{
    using System;
    using System.Data.Entity.Migrations;

    public partial class changedatattypeandaddedkeyId : DbMigration
    {
        public override void Up()
        {
            DropPrimaryKey("dbo.SchoolclassCodes");
            AddColumn("dbo.SchoolclassCodes", "Id", c => c.Int(nullable: false, identity: true));
            AlterColumn("dbo.SchoolclassCodes", "Schoolclass", c => c.String());
            AddPrimaryKey("dbo.SchoolclassCodes", "Id");
        }

        public override void Down()
        {
            DropPrimaryKey("dbo.SchoolclassCodes");
            AlterColumn("dbo.SchoolclassCodes", "Schoolclass", c => c.Int(nullable: false, identity: true));
            DropColumn("dbo.SchoolclassCodes", "Id");
            AddPrimaryKey("dbo.SchoolclassCodes", "Schoolclass");
        }
    }
}

当我运行 update-database 我得到一个例外，表中不允许有多个标识列。

When I run the update-database I get the exception that multiple identity columns are not allowed for a table.

但是我没有多个键

有谁知道如何解决这个问题？

Does anyone know how to solve this?

推荐答案

尝试移动

AlterColumn("dbo.SchoolclassCodes", "Schoolclass", c => c.String());

以上

AddColumn("dbo.SchoolclassCodes", "Id", c => c.Int(nullable: false, identity: true));

所以

public override void Up()
{
       DropPrimaryKey("dbo.SchoolclassCodes");
       AlterColumn("dbo.SchoolclassCodes", "Schoolclass", c => c.String());
       AddColumn("dbo.SchoolclassCodes", "Id", c => c.Int(nullable: false, identity: true));
       AddPrimaryKey("dbo.SchoolclassCodes", "Id");
}

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