Mega Code Archive
Sending data from database by portions
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Title: Sending data from database by portions
Question: Some times we need send hugo quantity of data from MiddleWare Server to client application. If we do it one portion than user mast wait long time, but we can send this data by portions, when user is needed in it.
Answer:
Some times we need send hugo quantity of data from MiddleWare Server to client application. If we do it one portion than user mast wait long time, but we can send this data by portions, when user is needed in it.
This is sample about getting portion of data from DataSetProvider and adding it to CLientDataSet.
In my article http://www.delphi3000.com/articles/article_3310.asp you can read how send data between applications usin INDY components.
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, Buttons, DB, DBTables, Provider, DBClient, Grids,
DBGrids, ExtCtrls, DBCtrls, IdBaseComponent,
IdAntiFreezeBase, IdAntiFreeze, JvSpecialProgress;
type
TForm1 = class(TForm)
DataSetProvider1: TDataSetProvider;
Table1: TTable;
BitBtn1: TBitBtn;
DBGrid1: TDBGrid;
DBGrid2: TDBGrid;
DataSource1: TDataSource;
DataSource2: TDataSource;
ClientDataSet1: TClientDataSet;
BitBtn2: TBitBtn;
DBNavigator1: TDBNavigator;
IdAntiFreeze1: TIdAntiFreeze;
BitBtn3: TBitBtn;
JvSpecialProgress1: TJvSpecialProgress;
procedure BitBtn1Click(Sender: TObject);
procedure FormShow(Sender: TObject);
procedure BitBtn2Click(Sender: TObject);
procedure DBNavigator1Click(Sender: TObject; Button: TNavigateBtn);
procedure BitBtn3Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
data:OleVariant;
records:integer;
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.BitBtn1Click(Sender: TObject);
var
recs:integer;
j:integer;
begin
ClientDataSet1.Active:=False;
data:=DataSetProvider1.GetRecords(1,recs,ResetOption+MetaDataOption);
Showmessage(format('get %d Records',[recs,i]));
ClientDataSet1.AppendData(data,False);
ClientDataSet1.Active:=True;
end;
procedure TForm1.FormShow(Sender: TObject);
begin
records:=DataSetProvider1.DataSet.RecordCount;
end;
procedure TForm1.BitBtn2Click(Sender: TObject);
var
recs:integer;
j:integer;
begin
data:=DataSetProvider1.GetRecords(-1,recs,ResetOption+MetaDataOption);
ClientDataSet1.AppendData(data,False);
ClientDataSet1.Active:=True;
end;
procedure TForm1.DBNavigator1Click(Sender: TObject; Button: TNavigateBtn);
var
recs:integer;
begin
case Button of
nbNext:begin
if DBNavigator1.DataSource.DataSet.RecordCount data:=DataSetProvider1.GetRecords(1,recs,ResetOption+MetaDataOption);
ClientDataSet1.AppendData(data,False);
end;
end;
nbPrior:begin
end;
nbLast:begin
if DBNavigator1.DataSource.DataSet.RecordCount data:=DataSetProvider1.GetRecords(-1,recs,ResetOption+MetaDataOption);
ClientDataSet1.AppendData(data,False);
end;
end;
nbFirst:begin
end;
end;
end;
procedure TForm1.BitBtn3Click(Sender: TObject);
var
recs:integer;
begin
JvSpecialProgress1.Maximum:=records;
JvSpecialProgress1.Position:=1;
while ClientDataSet1.RecordCount data:=DataSetProvider1.GetRecords(1,recs,ResetOption+MetaDataOption);
ClientDataSet1.AppendData(data,False);
JvSpecialProgress1.Position:=JvSpecialProgress1.Position+1;
end;
end;
end.
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