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Posted: **Sun 25 Mar 2012 19:43**

Im assigning a TMyquery to another TMyquery. Works fine until i try to access a calculated field - i get error "field XXX not found". I guess assign does not assign calculated fields, is there any workaround?

Posted: **Mon 26 Mar 2012 14:30**

Hello,

TMyQuery inherits basic functionality from the TDataSet class. The TDataSet.Assign method doesn't create fields in the destination dataset using fields from the source dataset. To solve the problem, you can use the following code:

Code: Select all

procedure TMainForm.ButtonClick(Sender: TObject);
var
  i: integer;
  fld: TField;
begin
  MyQuery1.Open;
  MyQuery2.Assign(MyQuery1);
  for i := 0 to MyQuery1.FieldCount - 1 do begin
    fld := TFieldClass(MyQuery1.Fields[i].ClassType).Create(MyQuery2);
    fld.FieldName := MyQuery1.Fields[i].FieldName;
    fld.FieldKind := MyQuery1.Fields[i].FieldKind;
    fld.DataSet := MyQuery2;
  end;
  MyQuery2.Open;
end;

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Assign TMyquery and calculated fields

Assign TMyquery and calculated fields