无法在表上创建多个聚集索引

本文介绍了无法在表上创建多个聚集索引的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

I am having the following error after typing update-database:

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

I am working on an Azure mobile service.

I have three data models:

public class AppUser : EntityData { public string Username { get; set; } public virtual ICollection<RatingItem> userRatings { get; set; } } public class PlaceItem : EntityData { public string PlaceName { get; set; } public int Group { get; set; } public string XCoordinate { get; set; } public string YCoordinate { get; set; } } public class RatingItem : EntityData { public int Ratings { get; set; } public string PlaceId { get; set; } public AppUser user { get; set; } }

It has to do with migration because :

• The initial create is in the _MigrationHistory table, but isn't in the migration folder in the solution explorer.
• When I add-migration AddAll, I don't get any errors, and AddAll appears in the migration folder, but not in the table.

In the context file:

public class ICbackendContext : DbContext { public DbSet<AppUser> AppUsers { get; set; } public DbSet<PlaceItem> PlaceItems { get; set; } public DbSet<RatingItem> RatingItems { get; set; }

}

解决方案

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.

To resolve this, run the database generator before migrations are applied. In the MigrationsConfiguration.cs file, include the following:

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

To learn more, see How to make data model changes to a .NET backend mobile service. The topic applies to both Mobile Services and Mobile Apps, though some namespaces are different in Mobile Apps.