C# 这取决于您采取的方法。使用代码优先的方法时，将DatabaseGenerated属性添加到键字段中。采用数据库优先的方法时，在模型上显式地将StoredGeneratedPattern设置为Identity [1]: https://i.stack.img

这取决于您采取的方法。使用代码优先的方法时，将DatabaseGenerated属性添加到键字段中。采用数据库优先的方法时，在模型上显式地将StoredGeneratedPattern设置为Identity

[1]: https://i.stack.imgur.com/IxGdd.png
[2]: https://i.stack.imgur.com/Qssea.png

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您是否尝试将注释

[DatabaseGenerated（DatabaseGeneratedOption.Identity）]

放在

公共Guid ID{get；set；}

之前？是否在表的初始生成之后添加了配置？在Ikian中，我认为fluent-api是首选，因为这里覆盖了

OnModelCreating

。我发现您还没有接受任何答案。你对什么都不满意吗？如果是这样，让我知道，我会发布另一个，这是有效的。只是觉得有点懒，不想输入，若我并没有得到代表：）谢谢你们的回答，但我在项目中首先使用代码。所以我不想手动创建数据库。@阿尔及尔达斯为什么刚才在每个实体的构造函数中都有一个Guid.NewGuid（）。我没有找到任何其他解决方案，所以我在构造函数中添加了Guid.NewGuid（）。Thanks@Algirdas仅供参考，Guid.NewGuid（）不会索引数据库中的内容。您应该使用顺序Guid，但是我认为通过覆盖OnModelCreating，您可以像使用此属性一样设置相同的设置。我来读这篇文章。感谢如果它是

主键

，则该字段中不可能有重复的guid键。因为

主键

将具有唯一的约束。数据库服务器将拒绝重复的主键。该Azure便笺确实为我节省了一些时间。谢谢。自Azure SQL V12以来，newsequentialid（）一直受支持。这是什么？我们在哪里使用它？“

Id=c.Guid（nullable:false，identity:true，defaultValueSql:”newsequentialid（）”，

“我知道已经有一段时间了，但是对于未来的读者，Id赋值语句会出现在codefirst迁移文件中。仅供参考：在ef7 RC1工作中[Key，DatabaseGenerated（DatabaseGeneratedOption.identity）]很好。。。但也只对新数据库进行了测试…这会创建碎片，对于小数据库来说这不是问题，但是大数据库应该使用顺序数据库guid@Miroslav，我假设您谈论的是我上面的答案，如果是，则不添加构造函数，当实体保存在数据库中时，数据库将创建一个顺序guid。

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<FileStore>().Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
    base.OnModelCreating(modelBuilder);
}

public class FileStore
 {
   [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
   public Guid Id { get; set; }
   public string Name { get; set; }
   public string Path { get; set; }
 }

.HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity)

[Id] [uniqueidentifier] NOT NULL DEFAULT newsequentialid(),

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }

Id = c.Guid(nullable: false, identity: true, defaultValueSql: "newsequentialid()"),

public class Carrier : Entity
{
    public Guid Id { get; set; }
    public string Code { get; set; }
    public string Name { get; set; }
}

public class CarrierMap : EntityTypeConfiguration<Carrier>
{
    public CarrierMap()
    {
        HasKey(p => p.Id);

        Property(p => p.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        Property(p => p.Code)
            .HasMaxLength(4)
            .IsRequired()
            .HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute { IsClustered = true, IsUnique = true }));

        Property(p => p.Name).HasMaxLength(255).IsRequired();
        Property(p => p.Created).HasPrecision(7).IsRequired();
        Property(p => p.Modified)
            .HasColumnAnnotation("IX_Modified", new IndexAnnotation(new IndexAttribute()))
            .HasPrecision(7)
            .IsRequired();
        Property(p => p.CreatedBy).HasMaxLength(50).IsRequired();
        Property(p => p.ModifiedBy).HasMaxLength(50).IsRequired();
        Property(p => p.Version).IsRowVersion();
    }
}

        CreateTable(
            "scoFreightRate.Carrier",
            c => new
                {
                    Id = c.Guid(nullable: false, identity: true),
                    Code = c.String(nullable: false, maxLength: 4),
                    Name = c.String(nullable: false, maxLength: 255),
                    Created = c.DateTimeOffset(nullable: false, precision: 7),
                    CreatedBy = c.String(nullable: false, maxLength: 50),
                    Modified = c.DateTimeOffset(nullable: false, precision: 7,
                        annotations: new Dictionary<string, AnnotationValues>
                        {
                            { 
                                "IX_Modified",
                                new AnnotationValues(oldValue: null, newValue: "IndexAnnotation: { }")
                            },
                        }),
                    ModifiedBy = c.String(nullable: false, maxLength: 50),
                    Version = c.Binary(nullable: false, fixedLength: true, timestamp: true, storeType: "rowversion"),
                })
            .PrimaryKey(t => t.Id)
            .Index(t => t.Code, unique: true, clustered: true);

CREATE TABLE [scoFreightRate].[Carrier] (
    [Id]         UNIQUEIDENTIFIER   DEFAULT (newsequentialid()) NOT NULL,
    [Code]       NVARCHAR (4)       NOT NULL,
    [Name]       NVARCHAR (255)     NOT NULL,
    [Created]    DATETIMEOFFSET (7) NOT NULL,
    [CreatedBy]  NVARCHAR (50)      NOT NULL,
    [Modified]   DATETIMEOFFSET (7) NOT NULL,
    [ModifiedBy] NVARCHAR (50)      NOT NULL,
    [Version]    ROWVERSION         NOT NULL,
    CONSTRAINT [PK_scoFreightRate.Carrier] PRIMARY KEY NONCLUSTERED ([Id] ASC)
);


GO
CREATE UNIQUE CLUSTERED INDEX [IX_Code]
    ON [scoFreightRate].[Carrier]([Code] ASC);

public class OurMigrationSqlGenerator : SqlServerMigrationSqlGenerator
{
    protected override void Generate(AddPrimaryKeyOperation addPrimaryKeyOperation)
    {
        if (addPrimaryKeyOperation == null) throw new ArgumentNullException("addPrimaryKeyOperation");
        if (!addPrimaryKeyOperation.Table.Contains("__MigrationHistory"))
            addPrimaryKeyOperation.IsClustered = false;
        base.Generate(addPrimaryKeyOperation);
    }

    protected override void Generate(CreateTableOperation createTableOperation)
    {
        if (createTableOperation == null) throw new ArgumentNullException("createTableOperation");
        if (!createTableOperation.Name.Contains("__MigrationHistory"))
            createTableOperation.PrimaryKey.IsClustered = false;
        base.Generate(createTableOperation);
    }

    protected override void Generate(MoveTableOperation moveTableOperation)
    {
        if (moveTableOperation == null) throw new ArgumentNullException("moveTableOperation");
        if (!moveTableOperation.CreateTableOperation.Name.Contains("__MigrationHistory")) moveTableOperation.CreateTableOperation.PrimaryKey.IsClustered = false;
        base.Generate(moveTableOperation);
    }
}

public class Carrier : Entity
{
    public Carrier()
    {
         this.Id = Guid.NewGuid();
    }  
    public Guid Id { get; set; }
    public string Code { get; set; }
    public string Name { get; set; }
}

public override void Up()
{
    AlterColumn("dbo.MyTable","Id", c =>  c.Guid(nullable: false, identity: true, defaultValueSql: "newsequentialid()"));
}

[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }

codefirst-defaultvalue

databasefirst-model

using (ApplicationDbContext context = new ApplicationDbContext())
{
    var person = new Person
                     {
                         FirstName = "Random",
                         LastName = "Person";
                     };

    context.People.Add(person);
    context.SaveChanges();
    Console.WriteLine(person.Id);
}

[1]: https://i.stack.imgur.com/IxGdd.png
[2]: https://i.stack.imgur.com/Qssea.png