用TdataSet设计主从表关系

      一般从数据库读出的数据必须经过处理，添加一些数据列才能满足我们的显示要求，这里

就可以用TdataSet为中介，把读取的数据处理后再显示到dbGrid上，废话不多，上代码呵

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, ADODB, StdCtrls, Grids, DBGrids, DBClient;

type
  TForm1 = class(TForm)
    Dbgrd1: TDBGrid;
    Dbgrd2: TDBGrid;
    Btn1: TButton;
    Con1: TADOConnection;
    Query1: TADOQuery;
    ClDsMaster: TClientDataSet;
    ClDsDetail: TClientDataSet;
    Ds1: TDataSource;
    Ds2: TDataSource;
    procedure FormCreate(Sender: TObject);
    procedure Btn1Click(Sender: TObject);
  private
    DSMaster: TDataSet;
    DSDetail: TDataSet;
    procedure CreateMemoryTable;
    procedure SumData;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var
  str : String;
begin
  str := 'Provider=Microsoft.Jet.OLEDB.4.0;Password="";Data Source=ReportData.mdb;Persist Security Info=True';
  Con1.Connected := False;
  Con1.ConnectionString := str;
  Con1.Connected := True;
end;

procedure TForm1.Btn1Click(Sender: TObject);
begin
  if not Query1.Active then
  Query1.Active := True;

  //建立内存表
  CreateMemoryTable;

  //汇总数据写入主数据集中
  SumData;
end;

procedure TForm1.CreateMemoryTable;
begin
   DSMaster:=TDataSet.Create(self);
   with DSMaster.FieldDefs do
   begin
     Add('分组',ftInteger,0,False);
     Add('数量',ftInteger,0,False);
     Add('金额',ftInteger,0,False);
   end;

   DSDetail := TDataSet.Create(Self);
    with dsDetail.FieldDefs do
    begin
        Add('分组',ftInteger,0,False);
        Add('编号',ftInteger,0,False);
        Add('名字',ftString,30,False);
        Add('数量',ftInteger,0,False);
        Add('金额',ftInteger,0,False);
    end;
    ClDsMaster.FieldDefs.Assign(DSMaster.FieldDefs);
    ClDsMaster.CreateDataSet;
    ClDsMaster.Open;

    ClDsDetail.FieldDefs.Assign(DSDetail.FieldDefs);
    ClDsDetail.CreateDataSet;
    ClDsDetail.Open;
end;

procedure TForm1.SumData;
const
  DEFAULT_PAGE_COUNT=20;
var
  iGroup,iNum,iMoney:integer;   //分组号,数量汇总，金额汇总
  bSum:Boolean;  //当前组是否已汇总
begin
  bSum:=False;
  iGroup:=1;
  iNum:=0;
  iMoney:=0;
  while not Query1.Eof do               //添加数据
  begin
    ClDsDetail.Append;
    ClDsDetail.FieldByName('分组').Value:=iGroup;
    ClDsDetail.FieldByName('编号').Value:=Query1.fieldByName('编号').Value;
    ClDsDetail.FieldByName('名字').Value := Query1.FieldByName('名字').Value;
    ClDsDetail.FieldByName('数量').Value := Query1.FieldByName('数量').Value;
    ClDsDetail.FieldByName('金额').Value := Query1.FieldByName('金额').Value;
    ClDsDetail.Post;
    bSum:=True;   //开始汇总
    inum:=iNum +query1.FieldByName('数量').value;
    iMoney:=iMoney+query1.fieldByName('金额').Value;
    if(Query1.RecNo mod DEFAULT_PAGE_COUNT)=0 then
    begin
      ClDsMaster.Append;
      ClDsMaster.FieldByName('分组').Value := iGroup;
      ClDsMaster.FieldByName('数量').Value := iNum;
      ClDsMaster.FieldByName('金额').Value := iMoney;
      ClDsMaster.Post;

      Inc(iGroup);
       bSum   := False;
      iNum   := 0;
      iMoney := 0;
    end;
    Query1.Next;
  end;
  if bSum then   //对不足一页的数据处理
  begin
    ClDsMaster.Append;
    ClDsMaster.FieldByName('分组').Value := iGroup;
    ClDsMaster.FieldByName('数量').Value := iNum;
    ClDsMaster.FieldByName('金额').Value := iMoney;
    ClDsMaster.Post;
  end;
end;

procedure TForm1.ClDsMasterAfterScroll(DataSet: TDataSet);
begin
  if not ClDsMaster.FieldByName('分组').IsNull then                      //添加的过滤功能
  begin
    ClDsDetail.Filtered := False;
    ClDsDetail.Filter := ' 分组=' + ClDsMaster.FieldByName('分组').AsString;
    ClDsDetail.Filtered := True;
  end;
end;

end.

完整程序：/Files/gaiyang/用TdataSet设计主从表.rar