LINQ ChangeConflictException Issue / Custom Property

Question

EDIT: I can't delete this post.  New thread in proper forum at http://social.msdn.microsoft.com/Forums/en-US/linqtosql/thread/a3d1b842-6782-459a-90f3-c9e503d01c35

I have a database table with project tasks. Each task is based on a task template, which is stored in the same table. Tasks inherit properties/fields from their associated task template record unless otherwise specified. I've created a self-referencing association in the datamodel for this table - TaskTemplateId points to the template's Id.

I am having tons of problems. I am getting a ChangeConflictException on updates even when I don't change any data in the table.

Am I going about this the right way, theoretically? Has anyone faced these issues before?

Column name X appears more than once in the result column list.

Here is an example property:

    public int NumberOfUnits
    {
        get
        {
            //If this is a task template return the actual database value
            if (IsTaskTemplate)
                return NumberOfUnitsPrivate;
            //If there is a task template override and NumberOfUnits has a value return that
            else if (IsTemplateOverride && NumberOfUnitsPrivate != 0)
                return NumberOfUnitsPrivate;

            //Else return the value in the task template record.
            if (TaskTemplateRecord != null)
                return TaskTemplateRecord.NumberOfUnitsPrivate;
            return 0;
        }
        set { NumberOfUnitsPrivate = value; }
    }

Some notes:

• I have set UpdateCheck to never on all the non-PK columns for this table.
• Thank you as always for your help.

EDIT: I can't delete this post.  New thread in proper forum at http://social.msdn.microsoft.com/Forums/en-US/linqtosql/thread/a3d1b842-6782-459a-90f3-c9e503d01c35

Answer 1

Hi markwilliamsps,

Are you using LINQ to SQL? If so, here is a more appropriate forum for this issue:

LINQ to SQL

http://social.msdn.microsoft.com/Forums/en-US/linqtosql/threads

If I misunderstood you, please let me know.

Thanks.

---

Bob Shen
MSDN Community Support | Feedback to us
Develop and promote your apps in Windows Store
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 2

I have a database table with project tasks. Each task is based on a task template, which is stored in the same table. Tasks inherit properties/fields from their associated task template record unless otherwise specified. I've created a self-referencing association in the datamodel for this table - TaskTemplateId points to the template's Id.

I am having tons of problems. I am getting a ChangeConflicException on updates even when I don't change any data in the table.

Am I going about this the right way, theoretically? Has anyone faced these two issues before?

Column name X appears more than once in the result column list.

Here is an example property:

    public int NumberOfUnits
    {
        get
        {
            //If this is a task template return the actual database value
            if (IsTaskTemplate)
                return NumberOfUnitsPrivate;
            //If there is a task template override and NumberOfUnits has a value return that
            else if (IsTemplateOverride && NumberOfUnitsPrivate != 0)
                return NumberOfUnitsPrivate;

            //Else return the value in the task template record.
            if (TaskTemplateRecord != null)
                return TaskTemplateRecord.NumberOfUnitsPrivate;
            return 0;
        }
        set { NumberOfUnitsPrivate = value; }
    }

Some notes:

• I have set UpdateCheck to never on all the non-PK columns for this table.

EDIT: So, here is the update statement that LINQ is sending to the server:

exec sp_executesql N'UPDATE [dbo].[ProjectTasks]
SET [NarrativeSourceTypeId] = @p0, [BillNarrative] = @p1
WHERE 0 = 1',N'@p0 nvarchar(4000),@p1 nvarchar(4000)',@p0=N'',@p1=N''

Is that not strange? Where 0 = 1? Below the code is fetching the project tasks from the server; it fires this code four times after that update statement.

exec sp_executesql N'SELECT [t0].[Id], [t0].[IsActive], [t0].[CmsMatterUno], [t0].[ProjectCategoryId], [t0].[ProjectStatusTypeId], [t0].[ProjectTemplateId], [t0].[Code], [t0].[Description], [t0].[StartDate], [t0].[FinishDate], [t0].[CreatedDate], [t0].[CreatedBy], [t0].[ModifiedDate], [t0].[ModifiedBy], [t1].[Id] AS [Id2], [t1].[IsActive] AS [IsActive2], [t1].[OrderBy], [t1].[ProjectTemplateId] AS [ProjectTemplateId2], [t1].[ProjectId], [t1].[ParentTaskId], [t1].[ProjectCategoryId] AS [ProjectCategoryId2], [t1].[IsTaskTemplate], [t1].[TaskTemplateId], [t1].[UnitTypeId] AS [UnitTypeIdPrivate], [t1].[DescriptionQualifierTypeId], [t1].[NarrativeSourceTypeId] AS [NarrativeSourceTypeIdPrivate], [t1].[CmsPhTaskUno] AS [CmsPhTaskUnoPrivate], [t1].[CmsBillTranUno], [t1].[Code] AS [Code2], [t1].[Description] AS [Description2], [t1].[IsPricingLevel], [t1].[IsCostingLevel], [t1].[NumberOfUnits] AS [NumberOfUnitsPrivate], [t1].[UnitPrice] AS [UnitPricePrivate], [t1].[StartDate] AS [StartDate2], [t1].[CompletionDate], [t1].[BillNarrative] AS [BillNarrativePrivate], [t1].[IsTemplateOverride], [t1].[BillingDate], [t1].[IsApprovalRequired], [t1].[IsTimeAssigned], [t1].[IsSummTimeOnBill], [t1].[IsAllowTime], [t1].[IsAllowBill], [t1].[IsAllowDisb], [t1].[CreatedDate] AS [CreatedDate2], [t1].[CreatedBy] AS [CreatedBy2], [t1].[ModifiedDate] AS [ModifiedDate2], [t1].[ModifiedBy] AS [ModifiedBy2], (
    SELECT COUNT(*)
    FROM [dbo].[ProjectTasks] AS [t2]
    WHERE [t2].[ProjectId] = [t0].[Id]
    ) AS [value]
FROM [dbo].[Projects] AS [t0]
LEFT OUTER JOIN [dbo].[ProjectTasks] AS [t1] ON [t1].[ProjectId] = [t0].[Id]
WHERE [t0].[CmsMatterUno] = @x2
ORDER BY [t0].[Id], [t1].[Id]',N'@x1 int,@x2 int',@x1=360930,@x2=536674

The update statement is being fired by a LinqDataSource within a UserControl. Everything happens in markup, save for the custom properties, an example of which is at the top.

As always, thank you for your help.

Answer 3

Hi Mark,

As far as I know, Sometimes it also happens if you’re joining two tables that have the same column name and you’re not running a natural join. For instance:

 

SELECT A.*, B.* FROM address A LEFT OUTER JOIN badaddress B

 

If A and B both have a field with the same name you’ll have the same problem.

Good day.

---

Alexander Sun [MSFT]
MSDN Community Support | Feedback to us
Develop and promote your apps in Windows Store
Please remember to mark the replies as answers if they help and unmark them if they provide no help.