不知道有没有好办法？

[waiwai88]

select distinct
a,
b,
c,
(select sum(g) from mytable where pk=t.pk and mytime='2005') as d,--今年的销量,
(select sum(g) from mytable where pk=t.pk and mytime='2005') as e,--去年的销量,
(select sum(g) from mytable where pk=t.pk and mytime='2005')/
(select sum(g) from mytable where pk=t.pk and mytime='2005') as f--今年销量　比　去年销量
from mytable t

不会每次用求和函数时都得用一个select吧，那么用d或e作运算的时候数据库是不是做了不少重复运算
能不能换个方法解决

[Big_Gun]

select sum(case when BillTypeObjID='0000000100000001' then IndiMoney else 0 end) X,
sum(case when BillTypeObjID='0000000400000001' then IndiMoney else 0 end) y,
sum(case when BillTypeObjID='0000000100000001' then IndiMoney else 0 end)/
sum(case when BillTypeObjID='0000000400000001' then IndiMoney else 0 end) N
from Indi_t_IndiBillDetail