oracle 的select 效率

SELECT TPROD, TTYPE,TRES,TCOM, TLOC,TQTY,TUMS,ORDERDATE,ORDERDEPARTMENT,idesc,bed_code,patient_sn,create_user,flag, 
source,orderid  from (SELECT  TPROD, TTYPE,TRES,TCOM, TLOC,TQTY,TUMS,ORDERDATE,ORDERDEPARTMENT,idesc,bed_code,patient_sn,create_user,flag,
INVITHI.source,INVITHI.orderid from(SELECT * FROM [email protected] WHERE 1=1 AND patient_sn>='300027181'AND 
patient_sn<='300027181') storeroom_ipd,INVITHI,iim   WHERE storeroom_ipd.source=INVITHI.source AND storeroom_ipd.ipd_order_no=INVITHI.orderid 
AND iim.iid='IM' and iim.iprod=INVITHI.tprod)
UNION ALL 
 (SELECT  TPROD, TTYPE,TRES,TCOM, TLOC,TQTY,TUMS,ORDERDATE,ORDERDEPARTMENT,idesc,' ' bed_code,patient_sn,create_user,flag,INVITHI.source,
 INVITHI.orderid from( SELECT * FROM [email protected] WHERE 1=1AND patient_sn>='300027181'AND patient_sn<='300027181') storeroom_opd,
 INVITHI,iim    WHERE INVITHI.source='0' AND storeroom_opd.opd_order_no=INVITHI.orderid AND iim.iid='IM' and  iim.iprod=INVITHI.tprod )
运行速度快，我一直都是60多秒