LINQ to SQL concurrency context - looks like a clean application with the correct row version

Question

I am trying to get LINQ to SQL to save changes to an attached object in which the support table has a DateTime column, which I suppose should function to control row versions as described.

The table looks like this:

CREATE TABLE [dbo].[client](
[client_id] [int] IDENTITY(1,1) NOT NULL,
[client_address1] varchar(100) NULL,
/* snip */
[modified_date] datetime NOT NULL,
CONSTRAINT [PK_CLIENT] PRIMARY KEY CLUSTERED ([client_id] ASC) )

The corresponding attributes in the modified_date property are set as follows in the DBML design:

Auto Generated Value: True
Auto-Sync: Always
Nullable: False
Primary Key: False
Read Only: False
Server Data Type: DateTime
Source: modified_date
Time Stamp: True
Update Check: Never

And the received attributes of the modified_date property declaration look correct, as far as I can tell:

[Column(Storage="_modified_date", AutoSync=AutoSync.Always, 
DbType="DateTime", IsDbGenerated=true, IsVersion=true, 
UpdateCheck=UpdateCheck.Never)]

The process of trying to save changes for the client looks something like this:

var c = new client { client_id = idOfClientToSave };

c.client_address1 = uxAddress1.Text;

// The DataContext is initialized in the constructor
// of ClientDataAccess
using (var ClientData = new ClientDataAccess())
{
    ClientData.SaveClient(c);
}

, , , , :

public int SaveClient(client c)
{
    c.modified_date = DateTime.Now.ToUniversalTime();

    if (c.client_id == 0)
    {
        _db.GetTable<client>().InsertOnSubmit(c);
    }
    else
    {
        _db.GetTable<client>().Attach(c, true);
    }
    try
    {
        _db.SubmitChanges(ConflictMode.ContinueOnConflict);
    }
    catch (ChangeConflictException)
    {
        foreach (var con in _db.ChangeConflicts)
        {
            con.Resolve(RefreshMode.OverwriteCurrentValues);
        }
        throw;
    }
}

_db.SubmitChanges(ConflictMode.ContinueOnConflict) - ChangeConflict ( _db.SubmitChanges()). , DataContext, DataContext .

.

Answer 1

.

else   
{
    _db.GetTable<client>().Attach(c, true);
    _db.Refresh(RefreshMode.KeepCurrentValues, c);
}

: concurrency ( ).