LINQ到SQL更新中的(C#变量的)默认值问题
我有以下代码用于使用LINQ将Account表更新为SQL。AccountNumber是主键列。唯一需要更新的值是AccountType;但是,持续时间也会更新为零(int的默认值)。我们如何避免这种不必要的覆盖 注意:我使用的是附加方法 注意:我理解这种行为的原因。“DataContext无法区分赋值为零的字段和未赋值的字段。”。我正在寻找克服这一问题的解决办法LINQ到SQL更新中的(C#变量的)默认值问题,c#,.net,sql-server,linq,linq-to-sql,C#,.net,Sql Server,Linq,Linq To Sql,我有以下代码用于使用LINQ将Account表更新为SQL。AccountNumber是主键列。唯一需要更新的值是AccountType;但是,持续时间也会更新为零(int的默认值)。我们如何避免这种不必要的覆盖 注意:我使用的是附加方法 注意:我理解这种行为的原因。“DataContext无法区分赋值为零的字段和未赋值的字段。”。我正在寻找克服这一问题的解决办法 [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Durati
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Duration", DbType="Int NOT NULL"
public int Duration
表数据
表结构:
CREATE TABLE [dbo].[Account](
[AccountNumber] [int] NOT NULL,
[AccountType] [nchar](10) NOT NULL,
[Duration] [int] NOT NULL,
[DepositedAmount] [int] 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]
代码
阅读:
这应该做到:
int number = 4;
var acc1 = new accountRepository.Accounts.Where(a => a.Number == number).FirstOrDefault();
if (acc1 == null)
{
// Not found by ID, create new
acc1 = new RepositoryLayer.Account();
acc1.Number = number;
accountRepository.Accounts.AddObject(acc1);
}
acc1.AccountType = "Verify";
accountRepository.SubmitChanges();
这应该做到:
int number = 4;
var acc1 = new accountRepository.Accounts.Where(a => a.Number == number).FirstOrDefault();
if (acc1 == null)
{
// Not found by ID, create new
acc1 = new RepositoryLayer.Account();
acc1.Number = number;
accountRepository.Accounts.AddObject(acc1);
}
acc1.AccountType = "Verify";
accountRepository.SubmitChanges();
我通过按照中的答案更改更新方法来解决这个问题 UpdateCheck在Duration列中设置为Never
public void UpdateAccount()
{
//Used value from previous select
DateTime previousDateTime = new DateTime(2012, 6, 26, 11, 14, 15, 327);
int prevDuration = 0;
RepositoryLayer.Account accEntity = new RepositoryLayer.Account();
accEntity.AccountNumber = 1; //Primary Key
accEntity.ModifiedTime = previousDateTime; //Concurrency column
//accEntity.Duration = prevDuration;
accountRepository.UpdateChangesByAttach(accEntity);
//Values to be modified after Attach
accEntity.AccountType = "WIN-WIN";
accEntity.ModifiedTime = DateTime.Now;
try
{
accountRepository.SubmitChanges();
}
catch(System.Data.Linq.ChangeConflictException e)
{
throw new Exception(e.Message);
}
}
public virtual void UpdateChangesByAttach(T entity)
{
if (Context.GetTable<T>().GetOriginalEntityState(entity) == null)
{
//If it is not already attached
Context.GetTable<T>().Attach(entity);
}
}
我通过按照中的答案更改更新方法来解决这个问题 UpdateCheck在Duration列中设置为Never
public void UpdateAccount()
{
//Used value from previous select
DateTime previousDateTime = new DateTime(2012, 6, 26, 11, 14, 15, 327);
int prevDuration = 0;
RepositoryLayer.Account accEntity = new RepositoryLayer.Account();
accEntity.AccountNumber = 1; //Primary Key
accEntity.ModifiedTime = previousDateTime; //Concurrency column
//accEntity.Duration = prevDuration;
accountRepository.UpdateChangesByAttach(accEntity);
//Values to be modified after Attach
accEntity.AccountType = "WIN-WIN";
accEntity.ModifiedTime = DateTime.Now;
try
{
accountRepository.SubmitChanges();
}
catch(System.Data.Linq.ChangeConflictException e)
{
throw new Exception(e.Message);
}
}
public virtual void UpdateChangesByAttach(T entity)
{
if (Context.GetTable<T>().GetOriginalEntityState(entity) == null)
{
//If it is not already attached
Context.GetTable<T>().Attach(entity);
}
}
谢谢当我们使用“附加”和刷新方法时,我们不能实现它吗?@Lijo:Attach过去只会给我带来问题。使用上述方法,而不是;p@leppie您能列出这些问题或提供参考吗?谢谢。当我们使用“附加”和刷新方法时,我们不能实现它吗?@Lijo:Attach过去只会给我带来问题。使用上述方法,而不是;p@leppie您能列出这些问题或提供参考吗?
UPDATE [dbo].[Account]
SET [AccountType] = @p2, [ModifiedTime] = @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) [6/26/2012 11:14:15 AM]
-- @p2: Input NChar (Size = 10; Prec = 0; Scale = 0) [WIN-WIN]
-- @p3: Input DateTime (Size = -1; Prec = 0; Scale = 0) [6/26/2012 11:16:29 AM]