I`ve been trying to get to know ADO.net lately and I wonder if anyone can
explain why the following does not work -

myDataSet.Clear();
myDataSet.AcceptChanges();
myTableAdapter.Update(myDataSet);

If you clear the dataset and then do the update shouldnt the database be
cleared as well. When I tried this the contents of the database are still
there when I rerun my app.

What I ended up doing was iterating throw the dataset and deleting row by
row but I`m curious why the above doesnt work.

TIA,

mick

In your case Clear removes all the information from *Dataset* thus Update
won't do anything. Update does its things based on the rows in their
RowState.

--
Miha Markic [MVP C#, INETA Country Leader for Slovenia]
RightHand .NET consulting & development www.rthand.com
Blog: blog.rthand.com


"mick" <(E-Mail Removed)> wrote in message
news:#(E-Mail Removed)...
> I`ve been trying to get to know ADO.net lately and I wonder if anyone can
> explain why the following does not work -
>
> myDataSet.Clear();
> myDataSet.AcceptChanges();
> myTableAdapter.Update(myDataSet);
>
> If you clear the dataset and then do the update shouldnt the database be
> cleared as well. When I tried this the contents of the database are still
> there when I rerun my app.
>
> What I ended up doing was iterating throw the dataset and deleting row by
> row but I`m curious why the above doesnt work.
>
> TIA,
>
> mick

"Miha Markic" <miha at rthand com> wrote in message
news:F39C4D09-1AA5-45F1-BE03-(E-Mail Removed)...
> In your case Clear removes all the information from *Dataset* thus Update
> won't do anything. Update does its things based on the rows in their
> RowState.
>

I`ve been reading a bit more and would just like you confirm that I
understand it correctly -

When I use Clear on the DataSet it actually clears all of the entries but if
I use Delete it just "marks" entries for deletion but does not actually
perform any deletion until the update. Is this correct?

mick

> I`ve been reading a bit more and would just like you confirm that I
> understand it correctly -
>
> When I use Clear on the DataSet it actually clears all of the entries but
> if I use Delete it just "marks" entries for deletion but does not actually
> perform any deletion until the update. Is this correct?

Yes, it will mark existing rows with RowState = Deleted. If the row doesn't
exist in database (it has been added in memory) it will be removed.

HTH,
--
Miha Markic [MVP C#, INETA Country Leader for Slovenia]
RightHand .NET consulting & development www.rthand.com
Blog: blog.rthand.com

"Miha Markic" <miha at rthand com> wrote in message
news:F5B8AF6B-99BD-4D30-ABEE-(E-Mail Removed)...
>
>> I`ve been reading a bit more and would just like you confirm that I
>> understand it correctly -
>>
>> When I use Clear on the DataSet it actually clears all of the entries but
>> if I use Delete it just "marks" entries for deletion but does not
>> actually perform any deletion until the update. Is this correct?
>
> Yes, it will mark existing rows with RowState = Deleted. If the row
> doesn't exist in database (it has been added in memory) it will be
> removed.

Thanks Miha.

mick