Error after performing migrations (.Net backend)

问题

My backend is built in .NET, and by including a table in the solution, I got the following error:

Cannot create more than one clustered index on table 'dbo.Favorit'. Drop the existing clustered index 'PK_dbo.Favorit' before creating another.

This code was generated after the Add-Migration CreateFavorit and update-database command:

namespace appService.Migrations
{
    using System;
    using System.Collections.Generic;
    using System.Data.Entity.Infrastructure.Annotations;
    using System.Data.Entity.Migrations;

    public partial class CreateFavorit : DbMigration
    {
        public override void Up()
        {
            CreateTable(
                "dbo.Favorit",
                c => new
                    {
                        Id = c.String(nullable: false, maxLength: 128,
                            annotations: new Dictionary<string, AnnotationValues>
                            {
                                { 
                                    "ServiceTableColumn",
                                    new AnnotationValues(oldValue: null, newValue: "Id")
                                },
                            }),
                        Nome = c.String(),
                        Lat_dest = c.Double(nullable: false),
                        Lon_dest = c.Double(nullable: false),
                        Id_usuario = c.String(),
                        Endereco = c.String(),
                        MeioTransporte = c.String(),
                        Id_usuario_2 = c.String(),
                        Version = c.Binary(nullable: false, fixedLength: true, timestamp: true, storeType: "rowversion",
                            annotations: new Dictionary<string, AnnotationValues>
                            {
                                { 
                                    "ServiceTableColumn",
                                    new AnnotationValues(oldValue: null, newValue: "Version")
                                },
                            }),
                        CreatedAt = c.DateTimeOffset(nullable: false, precision: 7,
                            annotations: new Dictionary<string, AnnotationValues>
                            {
                                { 
                                    "ServiceTableColumn",
                                    new AnnotationValues(oldValue: null, newValue: "CreatedAt")
                                },
                            }),
                        UpdatedAt = c.DateTimeOffset(precision: 7,
                            annotations: new Dictionary<string, AnnotationValues>
                            {
                                { 
                                    "ServiceTableColumn",
                                    new AnnotationValues(oldValue: null, newValue: "UpdatedAt")
                                },
                            }),
                        Deleted = c.Boolean(nullable: false,
                            annotations: new Dictionary<string, AnnotationValues>
                            {
                                { 
                                    "ServiceTableColumn",
                                    new AnnotationValues(oldValue: null, newValue: "Deleted")
                                },
                            }),
                    })
                .PrimaryKey(t => t.Id)
                .Index(t => t.CreatedAt, clustered: true);

        }

        public override void Down()
        {
            DropIndex("dbo.Favorit", new[] { "CreatedAt" });
            DropTable("dbo.Favorit",
                removedColumnAnnotations: new Dictionary<string, IDictionary<string, object>>
                {
                    {
                        "CreatedAt",
                        new Dictionary<string, object>
                        {
                            { "ServiceTableColumn", "CreatedAt" },
                        }
                    },
                    {
                        "Deleted",
                        new Dictionary<string, object>
                        {
                            { "ServiceTableColumn", "Deleted" },
                        }
                    },
                    {
                        "Id",
                        new Dictionary<string, object>
                        {
                            { "ServiceTableColumn", "Id" },
                        }
                    },
                    {
                        "UpdatedAt",
                        new Dictionary<string, object>
                        {
                            { "ServiceTableColumn", "UpdatedAt" },
                        }
                    },
                    {
                        "Version",
                        new Dictionary<string, object>
                        {
                            { "ServiceTableColumn", "Version" },
                        }
                    },
                });
        }
    }
}

Server microsoft-azure, database SQLServer. How to solve this? Or, what is this error? Thank you.

EDIT:

Model Class:

namespace appService.DataObjects
{
    public class Favorit : EntityData
    {
        public string Nome { get; set; }
        public double Lat_dest { get; set; }
        public double Lon_dest { get; set; }
        public string Id_usuario { get; set; }
        public string Endereco { get; set; }
        public string MeioTransporte { get; set; }
        public string Id_usuario_2 { get; set; }

    }
}

回答1:

We can include the following code in the Configuration.cs file to resolve it.

public Configuration()
{
   AutomaticMigrationsEnabled = false;
   SetSqlGenerator("System.Data.SqlClient", new EntityTableSqlGenerator());
}

The error message is caused by Entity framework doesn't have an annotation for creating a clustered index that is not a primary key. The mobile SDK manually creates the right SQL statements to set CreateAt as a non-primary key clustered index. More detail info please refer to another SO thread.

Generally, this error message is caused by not running the Mobile Apps/Mobile Services DB generator. Entity Framework does not have an annotation for creating a clustered index that is not a primary key, so the mobile server SDK manually creates the right SQL statements to set CreatedAt as a non-primary key clustered index.

I did a test for it, and it works correctly.The following is my detail steps:

1.Download the mobile project from azure portal

2.Add a new model in the project

3.Add property in the XXXContext.cs file

4.Add SetSqlGenerator("System.Data.SqlClient", new EntityTableSqlGenerator()) in the Configuration.cs file

5.Run enable-migrations -force, add-migration tomtest-somechange, update-database in the Package Manager console.

6 . Check the table is created correctly

来源：https://stackoverflow.com/questions/41962943/error-after-performing-migrations-net-backend