Select only changed DBGrid rows
lazarus / 16-Databases

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cobie1 · 2015-02-25 16:05

Anyone got an idea of how I can simply select the rows in the DBGrid
that have changed.

I don't want to apply updates to the file I have queried as changes to
this file have knock on effects to other files

Let's say. for instance, I select the Purchase file and want to change
the quantity on one of the records, but changing the purchase quantity
also affects the stock amount.

What I want to do is select only the rows that have changed and use
the info in that row to call a stored procedure to update both the
purchase file, the inventory file and possibly other files.

Any help is GREATLY appreciated from this newbie.

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LacaK · 2015-03-03 06:09

Do you use TSQLQuery -> TDataSource -> TDBGrid ?
May be you can try use something like:
1. OnFilterRecord event handler of TSQLQuery
2. in OnFilterRecord set Accept := SQLQuery1.UpdateStatus =
usModified;

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cobie1 · 2015-03-03 08:23

I've found a way to do it by reading through the DBGrid and comparing
the new value to the old value (see below), but what I would also like
to do is change the colour on the changed field to green if the called
procedure returns with 'Success' or red if it is 'Failed', but only
once I have read the row and processed it. At the moment I am building
a Stringgrid in line with the DBGrid as I read it to show the text
'Updated', 'Failed' or 'Not changed' based on the results.

To check for changed values I am using the following:-

 DBGrid1.DataSource.DataSet.DisableControls;
  for Rcount := 1 to dbgrid1.datasource.dataset.RecordCount do
    begin
      count := count + 1;
      dbgrid1.datasource.dataset.RecNo:=Rcount;
      // if SNP value has changed
      if DBGrid1.DataSource.DataSet.Fields[2].NewValue <>
         DBGrid1.DataSource.DataSet.Fields[2].oldValue then
      begin
         // Call the stored procedure to update the SNP
         srf:=DBGrid1.DataSource.DataSet.Fields[0].AsString;
         sqb:=DBGrid1.DataSource.DataSet.Fields[1].AsString;
         snp:=DBGrid1.DataSource.DataSet.Fields[2].AsString;
         ReturnStatus:='  ';
         ChangeSNP(srf, sqb, snp, ReturnStatus);

         // Populate the StringGrid to show  the updated rows
         if DBGrid1.DataSource.DataSet.Fields[2].NewValue <>
         DBGrid1.DataSource.DataSet.Fields[2].oldValue then
         begin
            Form2.Label5.caption:='Changing colours';
            StringGrid1.cells[0, RCount]:='Updated';
            StringGrid1.canvas.Brush.color:=clGreen;
         end
         else
         begin
            StringGrid1.canvas.Brush.color:=clRed;
            StringGrid1.cells[0, RCount]:='Failed';
         end;
      end;
      if DBGrid1.DataSource.DataSet.Fields[2].NewValue =
         DBGrid1.DataSource.DataSet.Fields[2].oldValue then
      begin
        StringGrid1.cells[0, RCount]:='Unchanged';
      end;
    end;
  DBGrid1.DataSource.DataSet.EnableControls;