SQL分组太多查询效率十分低，怎么改才能提高效率？求大神指教

select BUSCOMPANYNAME, LINENAME, BUSFREQUENCYTYPE,sum(VOUCHERPASSENGERSNUM) VOUCHERPASSENGERSNUM
,sum(MILEAGE) MILEAGE, sum(SEATQUANTITY) SEATQUANTITY, count(id) carCount,
sum(VOUCHERTURNOVER) VOUCHERTURNOVER, sum(EXTRATYPE) EXTRATYPE from

            (select tpc.BUSCOMPANYNAME, tpc.LINENAME, tpc.BUSFREQUENCYTYPE, tpc.VOUCHERPASSENGERSNUM, tpc.MILEAGE, tpc.VOUCHERTURNOVER,

            tpe.SEATQUANTITY, tpe.EXTRATYPE, tpe.id
            from TBRT_PASS_CUST tpc, TBRT_PASS_EXEBUS tpe
            where tpc.BUSCODE = tpe.BUSCODE
            and subStr(tpe.DEPARTTIME, 0, 7)>=? and subStr(tpe.DEPARTTIME, 0, 7)<=? 
            --Aand tpc.BUSCOMPANYCODE=?
            --Band tpc.BUSFREQUENCYTYPE=?
            --Cand tpc.LINECODE=?
            ) 
            group by BUSCOMPANYNAME, LINENAME, BUSFREQUENCYTYPE

使用inner join连接吧