如何从数据库 (ASP.NET MVC5) 中删除具有迁移约束的列

Question

每次我尝试使用以下迁移删除列时：

public partial class RemoveProject_Id1InAspNetUsers2 : DbMigration
    {
        public override void Up()
        {
            DropColumn("dbo.AspNetUsers", "Project_Id1");
        }

        public override void Down()
        {
        }
    }

我在 PMC 中 Update-Database 后出现以下错误：

The index 'IX_Project_Id1' is dependent on column 'Project_Id1'.
The object 'FK_dbo.AspNetUsers_dbo.Projects_Project_Id1' is dependent on column 'Project_Id1'.
ALTER TABLE DROP COLUMN Project_Id1 failed because one or more objects access this column.

这是我的 AspNetUser Table： dbo.AspNetUser DB Image

这是我的项目Class:

public class Project
{
    public int Id { get; set; }

    [DisplayName("Project Manager")]
    public string ProjectManagerId { get; set; }

    //        [ForeignKey("ProjectManagerId")]
    //        public ApplicationUser ProjectManager { get; set; }

    //public string ProjectMembersId { get; set; }

    //public List<ApplicationUser> ProjectMembers { get; set; }

    public virtual ICollection<ProjectResource> OurProjectResources { get; set; }

}

我已经尝试从我的项目中移除所有对 ApplicationUser 的引用 Class。

PS：我已经尝试 运行 此 SQL 语句的迁移： Sql("ALTER TABLE AspNetUsers DROP CONSTRAINT FK_AspNetUsers_Projects_Project_Id1"); 并给出一个错误：

'FK_AspNetUsers_Projects_Project_Id1' is not a constraint.
Could not drop constraint. See previous errors.

我正在使用 EF6 Code First 工作流。

This post 解释了问题所在，但我想了解如何编写迁移以从数据库中删除列。

Answer 1

首先，您需要指定错误中的约束名称：

'FK_AspNetUsers_Projects_Project_Id1' is not a constraint. Could not drop constraint. See previous errors.

因此，要删除约束，我们可以使用：

Sql("ALTER TABLE AspNetUsers DROP CONSTRAINT [FK_dbo.AspNetUsers_dbo.Projects_Project_Id1]");

然后，你得到错误，在字段上创建了一个索引：

The index 'IX_Project_Id1' is dependent on column 'Project_Id1'. ALTER TABLE DROP COLUMN Project_Id1 failed because one or more objects access this column.

我们也需要删除索引。

Sql("DROP INDEX [IX_Project_Id1] ON dbo.AspNetUsers ");