求开始累计、年初到本期累计的SQL

CREATE TABLE cs_f_CostStatus(
 [costKPIKey] [int] NULL,
 [orgKey] [int] NULL,
 [dayKey] [int] NULL,
 [actAmt] [numeric](19, 6) NULL,
 [balAmt] [numeric](19, 6) NULL,
 [recAmt] [numeric](19, 6) NULL,
)
在以上表结构，求实际产值actAmt、计量balAmt、回款recAmt的年累、开累,其中dayKey以200904的数字形式表示年月。

现有以下SQL，评价性能等方面的优缺点.
--一次求年累开累
select cs1.costKPIKey, cs1.orgKey, cs1.dayKey, sum(cs2.actAmt) as actAmtSum,
sum(cs2.balAmt) as balAmtSum, sum(cs2.recAmt) as recAmtSum,
sum(CASE WHEN (cs1.dayKey-(cs1.dayKey % 100)<=cs2.dayKey) THEN cs2.actAmt ELSE 0 END) as actAmtSumYear,
sum(CASE WHEN (cs1.dayKey-(cs1.dayKey % 100)<=cs2.dayKey) THEN cs2.balAmt ELSE 0 END) as balAmtSumYear,
sum(CASE WHEN (cs1.dayKey-(cs1.dayKey % 100)<=cs2.dayKey) THEN cs2.recAmt ELSE 0 END) as recAmtSumYear
from cs_f_CostStatus cs1
inner join cs_f_CostStatus cs2
on (cs1.costKPIKey=cs2.costKPIKey) and (cs1.orgKey=cs2.orgKey) and (cs1.dayKey>=cs2.dayKey)
group by cs1.costKPIKey, cs1.orgKey, cs1.dayKey
order by cs1.costKPIKey, cs1.orgKey, cs1.dayKey

--只求开累
select cs1.costKPIKey, cs1.orgKey, cs1.dayKey, sum(cs2.actAmt) as actAmtSumYear,
sum(cs2.balAmt) as balAmtSumYear, sum(cs2.recAmt) as recAmtSumYear
from cs_f_CostStatus cs1
inner join cs_f_CostStatus cs2
on (cs1.costKPIKey=cs2.costKPIKey) and (cs1.orgKey=cs2.orgKey) and (cs1.dayKey>=cs2.dayKey)
group by cs1.costKPIKey, cs1.orgKey, cs1.dayKey

--只求年累
select cs1.costKPIKey, cs1.orgKey, cs1.dayKey, sum(cs2.actAmt) as actAmtSumYear,
sum(cs2.balAmt) as balAmtSumYear, sum(cs2.recAmt) as recAmtSumYear
from cs_f_CostStatus cs1
inner join cs_f_CostStatus cs2
on (cs1.costKPIKey=cs2.costKPIKey) and (cs1.orgKey=cs2.orgKey) and (cs1.dayKey>=cs2.dayKey)
and (cs1.dayKey-(cs1.dayKey % 100)<=cs2.dayKey)
group by cs1.costKPIKey, cs1.orgKey, cs1.dayKey