在nhibernate / fluent nhibernate中有什么不同的GeneratedBy

我正在玩nhibernate和流利的nhibernate并且看着GeneratedBy并且有很多选择（序列，sequenceIdentity等），但我不知道他们大多数人做了什么 .

我看到例如3个Guid .

GeneratedBy.Guid();
GeneratedBy.GuidComb();
GeneratedBy.GuidNative();

我听说不使用Guid（）并使用GuidComb，因为它是专为处理数据库而设计的（它不会破坏索引） .

我不知道 GuidNative() 是什么 .

我也试图做

GeneratedBy.Native()

我认为这将使用MSSQl 2008使用的任何东西，但我遇到了它的问题

CREATE TABLE [dbo].[AutoIds](
    [Id] [int] NOT NULL,
    [Test] [varchar](50) NULL,
 CONSTRAINT [PK_AutoIds] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

我在想

Id(x => x.Id).GeneratedBy.Native();

nhibernate会自动为我生成一个Id（如果我使用combGuid（）就会这样做）但是当我尝试提交它时，我得到了

NHibernate.Exceptions.GenericADOException was caught
  Message=could not insert: [unitofwork.Models.Domain.AutoIds][SQL: INSERT INTO [AutoIds] (Test) VALUES (?); select SCOPE_IDENTITY()]
  Source=NHibernate
  SqlString=INSERT INTO [AutoIds] (Test) VALUES (?); select SCOPE_IDENTITY()
  StackTrace:
       at NHibernate.Id.Insert.AbstractReturningDelegate.PerformInsert(SqlCommandInfo insertSQL, ISessionImplementor session, IBinder binder)
       at NHibernate.Persister.Entity.AbstractEntityPersister.Insert(Object[] fields, Boolean[] notNull, SqlCommandInfo sql, Object obj, ISessionImplementor session)
       at NHibernate.Persister.Entity.AbstractEntityPersister.Insert(Object[] fields, Object obj, ISessionImplementor session)
       at NHibernate.Action.EntityIdentityInsertAction.Execute()
       at NHibernate.Engine.ActionQueue.Execute(IExecutable executable)
       at NHibernate.Event.Default.AbstractSaveEventListener.PerformSaveOrReplicate(Object entity, EntityKey key, IEntityPersister persister, Boolean useIdentityColumn, Object anything, IEventSource source, Boolean requiresImmediateIdAccess)
       at NHibernate.Event.Default.AbstractSaveEventListener.PerformSave(Object entity, Object id, IEntityPersister persister, Boolean useIdentityColumn, Object anything, IEventSource source, Boolean requiresImmediateIdAccess)
       at NHibernate.Event.Default.AbstractSaveEventListener.SaveWithGeneratedId(Object entity, String entityName, Object anything, IEventSource source, Boolean requiresImmediateIdAccess)
       at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.SaveWithGeneratedOrRequestedId(SaveOrUpdateEvent event)
       at NHibernate.Event.Default.DefaultSaveEventListener.SaveWithGeneratedOrRequestedId(SaveOrUpdateEvent event)
       at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.EntityIsTransient(SaveOrUpdateEvent event)
       at NHibernate.Event.Default.DefaultSaveEventListener.PerformSaveOrUpdate(SaveOrUpdateEvent event)
       at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.OnSaveOrUpdate(SaveOrUpdateEvent event)
       at NHibernate.Impl.SessionImpl.FireSave(SaveOrUpdateEvent event)
       at NHibernate.Impl.SessionImpl.Save(Object obj)
       at unitofwork.Models.Repository.StoreRepo.Create(AutoIds autoIds) in StoreRepo.cs:line 37
       at unitofwork.Models.Service.StoreService.CreateStore() inStoreService.cs:line 40
  InnerException: System.Data.SqlClient.SqlException
       Message=Cannot insert the value NULL into column 'Id', table 'TESTUoW.dbo.AutoIds'; column does not allow nulls. INSERT fails.
The statement has been terminated.
       Source=.Net SqlClient Data Provider
       ErrorCode=-2146232060
       Class=16
       LineNumber=1
       Number=515
       Procedure=""
       Server=(local)
       State=2
       StackTrace:
            at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
            at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
            at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
            at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
            at System.Data.SqlClient.SqlDataReader.ConsumeMetaData()
            at System.Data.SqlClient.SqlDataReader.get_MetaData()
            at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
            at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async)
            at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)
            at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
            at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method)
            at System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
            at System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader()
            at NHibernate.AdoNet.AbstractBatcher.ExecuteReader(IDbCommand cmd)
            at NHibernate.Id.IdentityGenerator.InsertSelectDelegate.ExecuteAndExtract(IDbCommand insert, ISessionImplementor session)
            at NHibernate.Id.Insert.AbstractReturningDelegate.PerformInsert(SqlCommandInfo insertSQL, ISessionImplementor session, IBinder binder)
       InnerException:

nhibernate可以不自动递增整数？这只是一件难以跟踪的事情，以便找出下一个数字吗？

我正在玩ids，因为我很震惊地得知我这样做的方式不是一个好方法（我在我的数据库中设置为自动递增int，这是我一直为ado.net和linq做的事情 . SQL） .

每次执行保存时，都会发生对数据库的额外查询（获取pk） . 所以我正在玩，看看是什么组合导致这种情况发生 .

我开始更倾向于使用Guid（即使我更喜欢使用更短的内容，因此如果你因为某些原因需要手动查看数据库，那么在其他表中匹配会更快） .

我在考虑hilo，但我不喜欢的是，如果我必须切换ORM来说实体框架可能不支持hilo . 再加上我听说使用HiLO，它可以很快地通过大量的id，使你需要更大的数据类型 .