Best Way of Deleting All Rows in a DataView

12 Feb 2006 3:24 PM

michael

If I create a DataView(i.e. dv) with a particular RowFilter and Sort, I
realize that I can't use a For Each to delete those rows because each
deletion changes the current view.

So that this won't work:
dim drv as DataRowView
for each drv in dv
   drv.delete()
next

If however I collect an array of DataRowViews by using the FindRows of the
DataView and then using a snippet such as this(which deletes the rows in
reverse order) the deletion of the group of filtered rows works fine:

Dim dv As New DataView(TheTable, TheRowFilter, TheSort,
DataViewRowState.CurrentRows)
                Dim drv() As DataRowView = dv.FindRows("SortKey")
                 For x = drv.GetUpperBound(0) To 0 Step -1
                     drv(x).Delete()
                Next

However, this seems more complicated that it should be.

Therefore, what is the best way to delete all the rows in a particular
DataView?

--
Michael Hockstein

12 Feb 2006 9:23 PM

W.G. Ryan eMVP

You probably want to hit the table that it's bound to directly and delete
those rows or if you must iterate the view, just do it with an index based
loop and delete the row one by one. That should do it for you.
Show quote

"michael" <howlinghound@nospam.nospam> wrote in message
news:D46F85C7-78AC-4D64-AC78-20D77A3D98BF@microsoft.com...
> If I create a DataView(i.e. dv) with a particular RowFilter and Sort, I
> realize that I can't use a For Each to delete those rows because each
> deletion changes the current view.
>
> So that this won't work:
> dim drv as DataRowView
> for each drv in dv
>   drv.delete()
> next
>
>
>
> If however I collect an array of DataRowViews by using the FindRows of the
> DataView and then using a snippet such as this(which deletes the rows in
> reverse order) the deletion of the group of filtered rows works fine:
>
> Dim dv As New DataView(TheTable, TheRowFilter, TheSort,
> DataViewRowState.CurrentRows)
>                Dim drv() As DataRowView = dv.FindRows("SortKey")
>                 For x = drv.GetUpperBound(0) To 0 Step -1
>                     drv(x).Delete()
>                Next
>
>
>
> However, this seems more complicated that it should be.
>
> Therefore, what is the best way to delete all the rows in a particular
> DataView?
> --
> Michael Hockstein

13 Feb 2006 1:10 AM

michael

The nice potential of using the DataView to do the deletions is the ability
to make a selection of rows via the RowFilter. You can't do that in the
DataTable. It would be nice if the DataView had a DeleteRows() method, that
way you could filter on the rows you wanted gone and then vaporize them in
one fell swoop.

--
Michael Hockstein

Show quote

"W.G. Ryan eMVP" wrote:

> You probably want to hit the table that it's bound to directly and delete
> those rows or if you must iterate the view, just do it with an index based
> loop and delete the row one by one. That should do it for you.
> "michael" <howlinghound@nospam.nospam> wrote in message
> news:D46F85C7-78AC-4D64-AC78-20D77A3D98BF@microsoft.com...
> > If I create a DataView(i.e. dv) with a particular RowFilter and Sort, I
> > realize that I can't use a For Each to delete those rows because each
> > deletion changes the current view.
> >
> > So that this won't work:
> > dim drv as DataRowView
> > for each drv in dv
> >   drv.delete()
> > next
> >
> >
> >
> > If however I collect an array of DataRowViews by using the FindRows of the
> > DataView and then using a snippet such as this(which deletes the rows in
> > reverse order) the deletion of the group of filtered rows works fine:
> >
> > Dim dv As New DataView(TheTable, TheRowFilter, TheSort,
> > DataViewRowState.CurrentRows)
> >                Dim drv() As DataRowView = dv.FindRows("SortKey")
> >                 For x = drv.GetUpperBound(0) To 0 Step -1
> >                     drv(x).Delete()
> >                Next
> >
> >
> >
> > However, this seems more complicated that it should be.
> >
> > Therefore, what is the best way to delete all the rows in a particular
> > DataView?
> > --
> > Michael Hockstein
>
>
>

13 Feb 2006 2:27 AM

Kevin Yu [MSFT]

Hi Michael,

I agree with Bill that it's better to delete the row from the original
DataTable. Because as you can see, if you delete the DataRowView in the
DataView, the DataView will change because of this deletion. Currently,
there is no DeleteRows method in the DataView. Sorry for the inconvenience.

Kevin Yu
=======
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13 Feb 2006 8:53 AM

Cor Ligthert [MVP]

michael,

I am not forever sure if this in 1.x and 2.x the same, not everything is
working as dynamicly in 1.x as it should be.

However let us assume it is like that. Than the collection is everytime
created new. Therefore you have to do it bottom up.

For i as integer = dv.count -1 to 0 step -1
dv(i).delete
Next

I hope this helps,

Cor