Error Message when updating fields
 

hi,
i have created a class called TNote this is my class:
TNote = Class(TObject)
NoteID : Integer;
Descr : String;
Note : String;
CreatedByIDF : Integer;
DateTimeStamp : TDateTime;
ApplicableUserID : integer;
end;
TNotes = Class(TList)
Note : TNote;
procedure ClearList;
procedure RetrieveFromDB; overload;
procedure RetrieveFromDB(AWhereClause: String); Overload;
procedure Save(ATask: TNote);
procedure Update(ATask: TNote);
procedure FillObject(AControl: TWinControl);
procedure Delete(ANote : TNote);
class function Singleton: TNotes;
end;
i want to update the current field of TNote with values from the edit boxes,dont want to create an instance of TNote everytime i update a record. The changes must be updated in the database.I have used ADOQuery object for my sql. Is it possible not to create the instance of TNote everytime i update? Please help