一句SQL的优化？-----在线等待
具体功能是指带3个参数的sql查询语句，
1,开始时间（fromdate）不为空则应该大于该时间
2,结束时间（todate）不为空则应该小于该时间
3,工作组（workclass）为空选出所有的组
三者都可能为空的。
问题有没有更简单的SQL，应该怎么优化？

SELECT         *
FROM     DR_GROUP_CONFIG
WHERE          
(:fromdate   IS   NOT   NULL)   AND   (:todate   IS   NOT   NULL)   AND   (:workclass   IS   NOT   NULL)   AND   (FROM_DATE   > =   :fromdate)   AND   (TO_DATE   <=   :todate)   AND   (WORK_CLASS   =   :workclass)  

OR   (:fromdate   IS   NOT   NULL)   AND   (:todate   IS   NULL)   AND   (:workclass   IS   NOT   NULL)   AND   (FROM_DATE   > =   :fromdate)   AND   (WORK_CLASS   =   :workclass)  

OR   (:fromdate   IS   NULL)   AND   (:todate   IS   NOT   NULL)   AND   (:workclass   IS   NOT   NULL)   AND   (TO_DATE   <=   :todate)   AND   (WORK_CLASS   =   :workclass)  

OR   (:fromdate   IS   NULL)   AND   (:todate   IS   NULL)   AND   (:workclass   IS   NOT   NULL)   AND   (WORK_CLASS   =   :workclass)  

OR   (:fromdate   IS   NOT   NULL)   AND   (:todate   IS   NOT   NULL)   AND   (:workclass   IS   NULL)   AND   (FROM_DATE   > =   :fromdate)   AND   (TO_DATE   <=   :todate)  

OR   (:fromdate   IS   NOT   NULL)   AND   (:todate   IS   NULL)   AND   (:workclass   IS   NULL)   AND   (FROM_DATE   > =   :fromdate)  

OR   (:fromdate   IS   NULL)   AND   (:todate   IS   NOT   NULL)   AND   (:workclass   IS   NULL)   AND   (TO_DATE   <=   :todate)  

OR   (:fromdate   IS   NULL)   AND   (:todate   IS   NULL)   AND   (:workclass   IS   NULL)   AND   (1   =   1)

ORDER   BY   FROM_DATE

FROM后面的语句，有没有可以优化的？

------解决方案--------------------
先判断3个值，再组合sql语句，好一点吧，直接写太累了
------解决方案--------------------
SELECT *
FROM DR_GROUP_CONFIG
WHERE 1=1

if .....

if .....
------解决方案--------------------
MERGE INTO DR_GROUP_CONFIG t1
using (SELECT nvl(:fromdate, '19010101 ') begin_date,nvl(:todate end_date, '20991231 '),
:workclass workclass FROM dual) t2
on (t1.FROM_DATE> =t2.begin_date and t2.workclass is null
)
when matched then
select * from DR_GROUP_CONFIG;
WHEN NOT MATCHED THEN
MERGE INTO DR_GROUP_CONFIG t1
using (SELECT nvl(:fromdate, '19010101 ') begin_date,nvl(:todate end_date, '20991231 '),
:workclass workclass FROM dual) t2
on (t1.FROM_DATE> =t2.begin_date and t2.workclass is not null
)
when matched then
select * from DR_GROUP_CONFIG t where t.WORK_CLASS=t2.workclass;
------解决方案--------------------
忘了，把FROM_DATE和to_date加个to_char()