TADODataset Problem

I have only used query with Database table. how to use a query for calculated field?
Note: I am still a beginner in Delphi.

Drop an AdoQuery on your form,
connect it to your AdoConnection, and  

With AdoQuery do
  begin
  Close;
  Sql.Clear;
  Sql.Add('update my_table_name set days = 20')
  Sql.Add(' where my_key_field_name = :x');
  Parameters.parambyname('x').value := my_key_field_value
  ExecSql;
end;

The information i am trying to display is not even in the database. it is a calculated field. Also the TADODataset was working fine in my other applications.

I have so many graphs with the TADOdataset. So i would like to know how to use them.

Thanks

Please give me fields description(dataset) and more details about the task, so I can elaborate solution for you.

Here is a sample project i created  I added a TDBChart with Bar series. Linked it with a dataset (Tadodataset). Created a calculated field 'days' int he dataset.

I just want a single bar chart with the value i assign to it.

Sorry, if i have not given enough information. Just ask me.




unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, ADODB, TeEngine, Series, ExtCtrls, TeeProcs, Chart, DBChart;

type
  TForm1 = class(TForm)
    DBChart1: TDBChart;
    Series1: TBarSeries;
    ADODataSet1: TADODataSet;
    ADODataSet1days: TIntegerField;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  ADODataSet1.Close;
  ADODataSet1.CreateDataset;
  ADODataSet1.Insert;
  ADODataSet1.FieldByName('days').Value := 0;
  ADODataSet1.Post;
end;

end.

if it's a static calculated field, why not use the sql in the TADOQuery ?
SELECT A.*, 20 AS DAYS FROM TABLE


for Calculated fields, you need to set the OnCalcFields event
this calcs Test field (calculated) as X + Y
procedure TForm1.ADOQuery1CalcFields(DataSet: TDataSet);
begin
  Dataset.FieldByName('TEST').AsInteger :=
    Dataset.FieldByName('X').AsInteger + Dataset.FieldByName('Y').AsInteger;
end;

you only set the calculated field in this event !

>>bokist
you will allways add the field days
add a check for the fieldname

     if FindField('DAYS') = nil then 
     begin
       Close;
       Sql.Clear;
       Sql.Add('alter my_table_name  add days integer null');  // adding new field to your table
       ExecSql;
       ...
     end;

                                              

1:
2:
3:
4:
5:
6:
7:
8:

calculated value is obtained from a calculation (2x2=4,calculated field is 4)
You are calculating what ?
create dataset?
What dataset?
What exactly are you tring to do here ?

Sorry was not able to try the solutions, will try it tomorrow and let u know.

Thanks