LINQ to SQL的：更新不刷新时“UpdateCheck的=从不”(LINQ to SQL:

我有在各个领域的“UpdateCheck的=从不”，除了一个外地账户的实体。该“ModifiedTime”字段使用“UpdateCheck的=始终”。其目的是 - 并发检查应根据“ModifiedTime”仅列。

对于测试的目的，我提供的C＃代码硬编码的“ModifiedTime”值。因此，有没有需要从数据库读取的任何值并发。不过该代码将更新只有当我呼吁刷新方法的数据库。这似乎很奇怪。任何方法来避免这种情况？

请参阅：“没有更新查询”一节http://msdn.microsoft.com/en-us/library/bb386929.aspx

注：我试图通过不使用刷新避免SELECT语句

生成的SQL

 SELECT [t0].[AccountNumber], [t0].[AccountType], [t0].[Duration], [t0].[DepositedAmount], [t0].[Prefernce], [t0].[Comment], [t0].[ModifiedTime]
 FROM [dbo].[Account] AS [t0]
 WHERE [t0].[AccountNumber] = @p0

-- @p0: Input Int (Size = -1; Prec = 0; Scale = 0) [1]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1

更新查询

UPDATE [dbo].[Account]
SET [AccountType] = @p2, [Duration] = @p3
WHERE ([AccountNumber] = @p0) 
AND ([ModifiedTime] = @p1)

-- @p0: Input Int (Size = -1; Prec = 0; Scale = 0) [1]
-- @p1: Input DateTime (Size = -1; Prec = 0; Scale = 0) [6/25/2012 5:08:32 PM]
-- @p2: Input NChar (Size = 10; Prec = 0; Scale = 0) [SUCESS]
-- @p3: Input Int (Size = -1; Prec = 0; Scale = 0) [2]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1

表结构

CREATE TABLE [dbo].[Account](
[AccountNumber] [int] NOT NULL,
[AccountType] [nchar](10) NOT NULL,
[Duration] [int] NOT NULL,
[DepositedAmount] [int] NULL,
[Prefernce] [int] NULL,
[Comment] [nvarchar](50) NULL,
[ModifiedTime] [datetime] NOT NULL,
 CONSTRAINT [PK_Account] PRIMARY KEY CLUSTERED 
(
[AccountNumber] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF,   ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

C＃代码

    public virtual void UpdateChangesByAttach(T entity)
    {

        if (Context.GetTable<T>().GetOriginalEntityState(entity) == null)
        {
            //If it is not already attached
            Context.GetTable<T>().Attach(entity);
            Context.Refresh(System.Data.Linq.RefreshMode.KeepCurrentValues, entity);
        }

    }

    public void UpdateAccount()
    {
        //Used value from previous select
        DateTime previousDateTime = new DateTime(2012, 6, 25, 17, 8, 32, 677);

        RepositoryLayer.Account accEntity = new RepositoryLayer.Account();
        accEntity.AccountNumber = 1;

        accEntity.AccountType = "SUCESS";
        accEntity.ModifiedTime = previousDateTime;
        accEntity.Duration = 2;

        accountRepository.UpdateChangesByAttach(accEntity);
        accountRepository.SubmitChanges();

    }

数据表

读：

的LINQ to SQL：如何更新的唯一领域而不检索整个实体
更新没有LINQ 2 SQL第一选择数据？
更新选择在LINQ to SQL
LINQ to SQL的更新多张行
默认值的问题（C＃的变量）在LINQ to SQL更新

由于@sgmoore。 Attach方法后设置为要更新的值。现在，这是工作。有什么还没有提高？

生成的SQL

UPDATE [dbo].[Account]
SET [AccountType] = @p2, [Duration] = @p3, [ModifiedTime] = @p4
WHERE ([AccountNumber] = @p0) 
      AND ([ModifiedTime] = @p1)

-- @p0: Input Int (Size = -1; Prec = 0; Scale = 0) [1]
-- @p1: Input DateTime (Size = -1; Prec = 0; Scale = 0) [6/25/2012 5:08:32 PM]
-- @p2: Input NChar (Size = 10; Prec = 0; Scale = 0) [NEXT]
-- @p3: Input Int (Size = -1; Prec = 0; Scale = 0) [4]
-- @p4: Input DateTime (Size = -1; Prec = 0; Scale = 0) [6/26/2012 10:29:19 AM]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1

码

    public void UpdateAccount()
    {
        //Used value from previous select
        DateTime previousDateTime = new DateTime(2012, 6, 25, 17, 8, 32, 677);

        RepositoryLayer.Account accEntity = new RepositoryLayer.Account();
        accEntity.AccountNumber = 1; //Primary Key
        accEntity.ModifiedTime = previousDateTime; //Concurrency column

        accountRepository.UpdateChangesByAttach(accEntity);

        //Values to be modified after Attach
        accEntity.AccountType = "NEXT";
        accEntity.ModifiedTime = DateTime.Now;
        accEntity.Duration = 4;

        accountRepository.SubmitChanges();

    }

    public virtual void UpdateChangesByAttach(T entity)
    {

        if (Context.GetTable<T>().GetOriginalEntityState(entity) == null)
        {
            //If it is not already attached
            Context.GetTable<T>().Attach(entity);
        }

    }