sql中参数过多利用变量替换参数的方法

工作中遇到一个需求，需要非常多的参数，例如如下sql，

select
ff.fundsc||’-‘||ff.fundtzfs||’-‘||ff.fundcjfl||’-‘||ff.fundonefl||’-‘||ff.fundtowfl catagory,
sf.scode,replace(sf.fund5,’型证券投资基金’,”)fund5,sf.fund4,sf.fund10,
(select to_date(tradedate,’yyyy-MM-dd’) from sdc_fundnetassetvalue where scode=sf.scode and tradedate in
(select max(tradedate) from sdc_fundnetassetvalue where scode=sf.scode and to_date(tradedate,’yyyyMMdd’)>=(to_date(20120801,’yyyyMMdd’)-10) and tradedate<=20120801) and rownum<2) trdatedate,
(select unitvalue from sdc_fundnetassetvalue where scode=sf.scode and tradedate in
(select max(tradedate) from sdc_fundnetassetvalue where scode=sf.scode and to_date(tradedate,’yyyyMMdd’)>=(to_date(20120801,’yyyyMMdd’)-10) and tradedate<=20120801) and rownum<2) fejz,
(select accumulatedunitvalue from sdc_fundnetassetvalue where scode=sf.scode and tradedate in
(select max(tradedate) from sdc_fundnetassetvalue where scode=sf.scode and to_date(tradedate,’yyyyMMdd’)>=(to_date(20120801,’yyyyMMdd’)-10) and tradedate<=20120801) and rownum<2) feljjz,
(select f30004_30002 from si_fund_30002 where f_fundcode=sf.scode and f_type=0 and f_tradingdate in
(select max(f_tradingdate) from si_fund_30002 where f_fundcode=sf.scode and to_date(f_tradingdate,’yyyyMMdd’)>=(to_date(20120801,’yyyyMMdd’)-10) and f_tradingdate<=20120801) and rownum<2) gqyzjzzzl,
(select f30006_30002 from si_fund_30002 where f_fundcode=sf.scode and f_type=0 and f_tradingdate in
(select max(f_tradingdate) from si_fund_30002 where f_fundcode=sf.scode and to_date(f_tradingdate,’yyyyMMdd’)>=(to_date(20120801,’yyyyMMdd’)-10) and f_tradingdate<=20120801) and rownum<2) gqyyjzzzl,
decode((select f30007_30002 from si_fund_30002 where f_fundcode=sf.scode and f_type=0 and f_tradingdate in
(select max(f_tradingdate) from si_fund_30002 where f_fundcode=sf.scode and to_date(f_tradingdate,’yyyyMMdd’)>=(to_date(20120801,’yyyyMMdd’)-10) and f_tradingdate<=20120801) and rownum<2),
null,’-‘,to_char((select f30007_30002 from si_fund_30002 where f_fundcode=sf.scode and f_type=0 and f_tradingdate in
(select max(f_tradingdate) from si_fund_30002 where f_fundcode=sf.scode and to_date(f_tradingdate,’yyyyMMdd’)>=(to_date(20120801,’yyyyMMdd’)-10) and f_tradingdate<=20120801) and rownum<2),’fm999999990.9999′)) gqsgyjzzzl,
row_number() over(partition by ff.fundsc||’-‘||ff.fundtzfs||’-‘||ff.fundcjfl||’-‘||ff.fundonefl||’-‘||ff.fundtowfl
order by decode((select f30007_30002 from si_fund_30002 where f_fundcode=sf.scode and f_type=0 and f_tradingdate in
(select max(f_tradingdate) from si_fund_30002 where f_fundcode=sf.scode and to_date(f_tradingdate,’yyyyMMdd’)>=(to_date(20120801,’yyyyMMdd’)-10) and f_tradingdate<=20120801) and rownum<2),