unit dm;

interface

uses
  SysUtils, Classes, ADODB, DB;

type
  Tdm2 = class(TDataModule)
    ADOConnection1: TADOConnection;
    ADOQuery1: TADOQuery;
    ADOQuery1DSDesigner: TWideStringField;
    ADOQuery1DSDesigner2: TBCDField;
    ADOQuery1DSDesigner3: TBCDField;
    ADOQuery1DSDesigner4: TDateTimeField;
    ADOQuery1DSDesigner5: TWideStringField;
    ADOQuery1total: TCurrencyField;
    ADOTable1: TADOTable;
    procedure ADOQuery1CalcFields(DataSet: TDataSet);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  dm2: Tdm2;

implementation

{$R *.dfm}

procedure Tdm2.ADOQuery1CalcFields(DataSet: TDataSet);
begin
   adoquery1total.Value :=ADOQuery1DSDesigner2.Value -
                          ADOQuery1DSDesigner3.value ;
end;

end.