unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Buttons, frxClass;

type
  TForm1 = class(TForm)
    MasterDS: TfrxUserDataSet;
    DetailDS: TfrxUserDataSet;
    BitBtn1: TBitBtn;
    frxReport1: TfrxReport;
    procedure MasterDSFirst(Sender: TObject);
    procedure MasterDSNext(Sender: TObject);
    procedure MasterDSPrior(Sender: TObject);
    procedure MasterDSCheckEOF(Sender: TObject; var Eof: Boolean);
    procedure MasterDSGetValue(const VarName: String; var Value: Variant);
    procedure DetailDSCheckEOF(Sender: TObject; var Eof: Boolean);
    procedure DetailDSFirst(Sender: TObject);
    procedure DetailDSGetValue(const VarName: String; var Value: Variant);
    procedure DetailDSNext(Sender: TObject);
    procedure DetailDSPrior(Sender: TObject);
    procedure BitBtn1Click(Sender: TObject);
  private
    MasterNo: Integer;
    DetailNo: Integer;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

const
  Master: array[1..3, 1..2] of ShortString = ( // master Id, master name
    ('1', 'master 1'),
    ('2', 'master 2'),
    ('3', 'master 3'));
  Detail: array[1..15, 1..2] of ShortString = ( // master Id, detail name
    ('1', 'detail 1.1'), ('1', 'detail 1.2'), ('1', 'detail 1.3'),
    ('1', 'detail 1.4'), ('1', 'detail 1.5'), ('2', 'detail 2.1'),
    ('2', 'detail 2.2'), ('2', 'detail 2.3'), ('2', 'detail 2.4'),
    ('2', 'detail 2.5'), ('3', 'detail 3.1'), ('3', 'detail 3.2'),
    ('3', 'detail 3.3'), ('3', 'detail 3.4'), ('3', 'detail 3.5'));


procedure TForm1.MasterDSFirst(Sender: TObject);
begin
  MasterNo := 1;
end;

procedure TForm1.MasterDSNext(Sender: TObject);
begin
  Inc(MasterNo);
end;

procedure TForm1.MasterDSPrior(Sender: TObject);
begin
  Dec(MasterNo);
end;

procedure TForm1.MasterDSCheckEOF(Sender: TObject; var Eof: Boolean);
begin
  Eof := MasterNo > High(Master);
end;

procedure TForm1.MasterDSGetValue(const VarName: String; var Value: Variant);
begin
  Value := Master[MasterNo][2];
end;

procedure TForm1.DetailDSFirst(Sender: TObject);
begin
  DetailNo := 1;
  while (not DetailDS.Eof) and (Detail[DetailNo][1] <> Master[MasterNo][1]) do
    Inc(DetailNo);
end;

procedure TForm1.DetailDSNext(Sender: TObject);
begin
  Inc(DetailNo);
  while (not DetailDS.Eof) and (Detail[DetailNo][1] <> Master[MasterNo][1]) do
    Inc(DetailNo);
end;

procedure TForm1.DetailDSPrior(Sender: TObject);
begin
  Dec(DetailNo);
  while (DetailNo > 1) and (Detail[DetailNo][1] <> Master[MasterNo][1]) do
    Dec(DetailNo);
end;

procedure TForm1.DetailDSCheckEOF(Sender: TObject; var Eof: Boolean);
begin
  Eof := DetailNo > High(Detail);
end;

procedure TForm1.DetailDSGetValue(const VarName: String; var Value: Variant);
begin
  Value := Detail[DetailNo][2];
end;

procedure TForm1.BitBtn1Click(Sender: TObject);
begin
  frxReport1.ShowReport();
end;

end.