DBGrid и переход по строкам

dbGrid.DataSource.DataSet.Refresh
dbGrid.DataSource.DataSet.Next

procedure ReopenQuery(AQuery: TADOQuery; AKeyFields: string); overload;
var
  I: integer;
  FList: TList;
  FFieldValues: variant;
  bSavePosition: boolean;
begin
  bSavePosition := AQuery.Active;
 
  with AQuery do begin
    if bSavePosition then begin
      FList := TList.Create;
      try
        GetFieldList(FList, AKeyFields);
        if FList.Count = 0 then begin
          FFieldValues := Fields[0].AsVariant;
          AKeyFields   := Fields[0].FieldName;
        end
        else if FList.Count = 1 then
          FFieldValues := TField(FList[0]).AsVariant
        else begin
          FFieldValues := VarArrayCreate([0, FList.Count-1], varVariant);
          for I := 0 to FList.Count - 1 do
            FFieldValues[I] := TField(FList[I]).AsVariant;
        end;
      finally
        FList.Free;
      end;
    end;
 
    Close;
    Open;
 
    try
      if bSavePosition and not (VarType(FFieldValues) in [varNull, varUnknown]) then
        Locate(AKeyFields, FFieldValues, []);
    except
    end;
  end;
end;

ReopenQuery(qryInvoice, 'InvoiceID')
ReopenQuery(qryInvoiceDetails, 'InvoiceID;ItemID')