delete from Tovar where N_Firm =(select RN_Firm from Contragent where Firma=''ООО Балтрыба'')
delete from Tovar where RN_Firm=(select * from Contragent where Firma=''ООО Балтрыба'')
delete from Tovar where RN_Firm=(select N_Firm from Contragent where Firma=''ООО Балтрыба'')
delete from tbl_tovar where rn_Proiz=select N_Firm from tbl_Contragent where Firma=''ООО Балтрыба''