unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Grids, DBGrids, DB, DBTables;

type
  TForm1 = class(TForm)
    Table1: TTable;
    DataSource1: TDataSource;
    DBGrid1: TDBGrid;
    Table1Field2Salary: TCurrencyField;
    Table1EmpNo: TIntegerField;
    Table1LastName: TStringField;
    Table1FirstName: TStringField;
    Table1PhoneExt: TStringField;
    Table1HireDate: TDateTimeField;
    Table1Salary: TFloatField;
    procedure Table1CalcFields(DataSet: TDataSet);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Table1CalcFields(DataSet: TDataSet);
begin
  Table1.FieldByName('2Salary').AsCurrency:=Table1.FieldByName('Salary').AsCurrency *2;
end;

end.