Question

相关实体如下：

public class FieldBookingDateRange : ITimeStamps, ICreatedBy, ISoftDeletable
{
    [Key, DatabaseGenerated( DatabaseGeneratedOption.None )]
    public int FieldBookingDateRangeID { get; set; }

    [Required]
    public virtual FieldBooking FieldBooking { get; set; }

    public virtual DateRange DateRange { get; set; }

    ....
}

我有一个数据库列，当前设置为Identity：true。

如果我在其上运行以下自动生成的迁移（这应该在标识上将列设置为false）：

public partial class RemovedDBGen_FieldBookingDateRange : DbMigration
{
    public override void Up()
    {
        DropIndex("dbo.FieldBookingDateRanges", new[] { "FieldBookingDateRangeID" });
        DropPrimaryKey("dbo.FieldBookingDateRanges");
        AlterColumn("dbo.FieldBookingDateRanges", "FieldBookingDateRangeID", c => c.Int(nullable: false, identity: false));
        AddPrimaryKey("dbo.FieldBookingDateRanges", "FieldBookingDateRangeID");
        CreateIndex("dbo.FieldBookingDateRanges", "FieldBookingDateRangeID");
    }

    public override void Down()
    {
        DropIndex("dbo.FieldBookingDateRanges", new[] { "FieldBookingDateRangeID" });
        DropPrimaryKey("dbo.FieldBookingDateRanges");
        AlterColumn("dbo.FieldBookingDateRanges", "FieldBookingDateRangeID", c => c.Int(nullable: false, identity: true));
        AddPrimaryKey("dbo.FieldBookingDateRanges", "FieldBookingDateRangeID");
        CreateIndex("dbo.FieldBookingDateRanges", "FieldBookingDateRangeID");
    }
}

它没有做任何事......但不会失败。

为什么这不起作用？

SQL -Verbose输出

IF EXISTS (
    SELECT name FROM sys.indexes 
    WHERE 
        name = N'IX_FieldBookingDateRangeID' AND 
        object_id = object_id(N'[dbo].[FieldBookingDateRanges]', N'U')
)
DROP INDEX [IX_FieldBookingDateRangeID] ON [dbo].[FieldBookingDateRanges]
ALTER TABLE [dbo].[FieldBookingDateRanges] DROP CONSTRAINT [PK_dbo.FieldBookingDateRanges]
ALTER TABLE [dbo].[FieldBookingDateRanges] ALTER COLUMN [FieldBookingDateRangeID] [int] NOT NULL
ALTER TABLE [dbo].[FieldBookingDateRanges] ADD CONSTRAINT [PK_dbo.FieldBookingDateRanges] PRIMARY KEY ([FieldBookingDateRangeID])
CREATE INDEX [IX_FieldBookingDateRangeID] ON [dbo].[FieldBookingDateRanges]([FieldBookingDateRangeID])

Answer 1

我认为一旦设置了列，就无法从列中删除标识属性。但是，您可以修改自动生成的迁移以实现变通方法。

你可以在这里找到一些例子：

Remove Identity from a column in a table
如果您需要保留数据，但删除了IDENTITY列，则需要：
- 创建新列
- 将数据从现有IDENTITY列传输到新列
- 删除现有的IDENTITY列。
https://dba.stackexchange.com/questions/87420/how-to-remove-identity-specification-for-multiple-tables

身份列未被实体框架

1 个答案: