Scrolling within datagrid

[Heike]

I have a datagrid with its DataSource set to a dataset.

 

The first time the user clicks on the button "show" 25 records are read.

 

Now I need the following functionality:

If the user scrolls down and the last record is reached, the next 25 records should be read.

 

This is how I tried to do it:

 

Private Sub grdDataGrid_Scroll(...) Handles grdDataGrid.Scroll
   Dim intShowAnzahl As Integer
   Try
       intShowAnzahl = dgcTopLeftVisibleCell.RowNumber + Me.grdDataGrid.VisibleRowCount
       If intShowAnzahl = intSatzAnzahl Then
           DataGridLoadNext()
       End If
   Catch ex As Exception
       ErrorMessage(...)
   End Try
End Sub

Private Sub DataGridLoadNext(Optional ByVal blnSetPoint As Boolean = False)
   Dim intNewAnz As Integer
   Dim intAktAnz As Integer
   Try
       If mblnFirst Then
           mblnFirst = False
           DataGridLoad()
       Else
           If intSatzAnzahl > 0 And intSatzAnzahl < objIBS_Query.lngMaxReadRecord Then
               blnSatzAnzahlEnde = True
           End If
           If blnSatzAnzahlEnde = False Then
               Me.Cursor = Windows.Forms.Cursors.WaitCursor
               intAktAnz = Me.BindingContext(Me.DseDataSetPatient1, "KHSPET0").Count
               intSatzAnzahl = intAktAnz
               objIBS_Query.DataAdapterFillWaiting(objIBS_Query.dadDataAdapterPatient, Me.DseDataSetPatient1, intSatzAnzahl, CInt(objIBS_Query.lngMaxReadRecord), "KHSPET0")
               DataGridFormat()
               If blnSetPoint = True Then
                   If Me.grdDataGrid.RowCount > 0 Then 'hb130103
                       poiPointInCell00 = New Point(Me.grdDataGrid.GetCellBounds(0, 0).X + 4, Me.grdDataGrid.GetCellBounds(0, 0).Y + 4)
                   End If
               End If
               intNewAnz = Me.BindingContext(Me.DseDataSetPatient1, "KHSPET0").Count
               If intAktAnz = intNewAnz Then
                   blnSatzAnzahlEnde = True
               End If
               If intSatzAnzahl > intNewAnz Then
                   blnSatzAnzahlEnde = True
               End If
               intSatzAnzahl = intNewAnz
               Me.Cursor = Windows.Forms.Cursors.Default
               Me.grdDataGrid.Refresh()
           End If
       End If
   Catch ex As Exception
       ErrorMessage(...)
   Finally
   End Try
End Sub

 

Sometimes this works fine. But sometimes it seems that the scroll event is fired again and again.

Or in some other cases I only get an hourglass and nothing happens.

 

Any idea what I may have forgotten?

[AlexCode]

The point is...

Does this work worth the effort?

 

Your problem is the time you wait while the DataSet is populated with a huge database isn't it?

 

I don't know where the data comes from but I assume is coming from SQL server 2000... Is it? IF so, it gives you a functionality called CURSORS that does quite what you're looking for. Read some SQL Books (can find some good ones on kazaa).

 

You can also listen to Nerseus on this thread...

http://www.xtremedotnettalk.com/t49767.html

Edited September 29, 2003 by AlexCode

[Heike]

No, my problem is not the waiting time. Because I only read 25 records a time, it is fast enough.

 

My problem is that I seem to use the scroll event the wrong way or something like that.

 

I am not working with SQL Server 2000; I work with an iSeries.