Question

I have a form which contains a data grid and a save button.

When the user clicks the save button I check for new rows by checking a specific column. If its value is 0 I insert the row to database, and if the column value is not 0 then I update that row.

I can insert correctly but when updating an exception occurs:

ChangeConflictException was unhandled,1 of 6 updates failed.

I have checked the update statement and I’m sure it’s correct. What is the problem, can any one help me?

int id;
for (int i = 0; i < dgvInstructores.Rows.Count - 1; i++)
{
    id = int.Parse(dgvInstructores.Rows[i].Cells["ID"].Value.toString());
    if (id == 0)
    {
        dataClass.procInsertInstructores(name, nationalNum, tel1, tel2, 
                                            address, email);
        dataClass.SubmitChanges();
    }
    else
    {
        dataClass.procUpdateInstructores(id, name, nationalNum, tel1, tel2, 
                                            address, email);
        dataClass.SubmitChanges();
    }
}

I’m using linq to query sql server2005 database and vs2008

the stored procedure for ‘procUpdateInstructores’ is :

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go

ALTER proc [dbo].[procUpdateInstructores]
@ID int,
@name varchar(255),
@NationalNum varchar(25),
@tel1 varchar(15),
@tel2 varchar(15),
@address varchar(255),
@email varchar(255)
as
begin

BEGIN TRANSACTION

update dbo.Instructores
set
Name = @name , NationalNum = @NationalNum ,
tel1 = @tel1 , tel2 = @tel2 , address = @address , email = @email
where ID = @ID

IF (@@ROWCOUNT > 0) AND (@@ERROR = 0)
     BEGIN
          COMMIT TRANSACTION
     END
ELSE
     BEGIN
          ROLLBACK TRANSACTION
     END
end

Answer 1

In my experience, (working with .net forms and mvc with linq-to-sql) I have found that several times if the form collection contains the ID parameter of the data object then the update surely fails.

Even if the ID is the actual ID, it is still flagged as ‘propertyChanged’ when you bind it or update it or assign to another variable.

As such can we see the code for your stored procs? More specifically, the update proc?

The code you have posted above is fine, the exception should be coming from your stored proc.

However if you are confident that the proc is correct then perhaps look at the HTML code being used to generate the table. Some bugs might be present with respect to 0/1 on ID columns, etc.