对DBGrid的巧妙用法实现查询

void __fastcall TForm1::DBGrid2DblClick(TObject *Sender)
{
  // INGOODS‘ 是进货表

   int sumno=0,i;

   INGOODS->Edit();
file://-----------------------------------------------------
   AnsiString thisgoodsname;
   DBGrid2->SelectedIndex=1;
   thisgoodsname=DBGrid2->SelectedField->Value;
   file://ShowMessage(thisgoodsname);
//
file://-----------------------------------------------------
   Query2->Close();
   Query2->SQL->Clear();
   Query2->DatabaseName=\".\\\\\";
   Query2->SQL->Add(\"Select * from INGOODS\");
   Query2->SQL->Add(\"where GOODSNAME=\'\"+thisgoodsname+\"\'\");
   Query2->Prepare();
   Query2->Open();
   for(i=0;i<Query2->RecordCount;i++){
      sumno+=Query2->FieldByName(\"INGOODSNO\")->AsInteger;
      Query2->Next();
   }
   Form4=new TForm4(this);
   Form4->DBText1->DataSource=DataSource1;
   Form4->DBText1->DataField=\"ID\";
   Form4->DBText2->DataSource=DataSource1;
   Form4->DBText2->DataField=\"GOODSNAME\";
   Form4->DBText3->DataSource=DataSource1;
   Form4->DBText3->DataField=\"CLASS\";
   Form4->DBText4->DataSource=DataSource1;
   Form4->DBText4->DataField=\"THENMAN\";
   Form4->Label5->Caption=\"最近出货时间： \";
   Form4->DBText5->DataSource=DataSource1;
   Form4->DBText5->DataField=\"LASTTIME\";
   Form4->Label6->Caption=\"现总销售量：\";
   file://Form4->DBText6->DataSource=DataSource1;
   file://Form4->DBText6->DataField=\"THISGOODSNO\";
   Form4->Label7->Caption=IntToStr(sumno);
   file://Form4->Edit2->Text=
   Form4->Show();
}