SELECT tbl_Orders.id, tbl_Orders.FirmaUnvani, tbl_Orders.HizmetTuru, tbl_Orders.SozlesmeNo, tbl_Orders.BelirlenenUcret, Sum(tbl_Bills.FaturaTutar) AS ToplaFaturaTutar, IIf(Not IsNull([tbl_Bills].[FaturaTutar]),Nz([tbl_Bills].[FaturaTutar])/Nz([tbl_Orders].[BelirlenenUcret]),0) AS İfade1

FROM tbl_Orders LEFT JOIN tbl_Bills ON tbl_Orders.id = tbl_Bills.Sozlesme_id

GROUP BY tbl_Orders.id, tbl_Orders.FirmaUnvani, tbl_Orders.HizmetTuru, tbl_Orders.SozlesmeNo, tbl_Orders.BelirlenenUcret, IIf(Not IsNull([tbl_Bills].[FaturaTutar]),Nz([tbl_Bills].[FaturaTutar])/Nz([tbl_Orders].[BelirlenenUcret]),0);

Fatura tutarı boş olanlara 0 atar