資料庫的表，對這張表進行查詢、篩選等操作
pwr_1>0同時pwr_2>pwr_1,將pwr的和輸出。值578
select
case
when
sum(pwr)
isnot
null
then
sum(pwr)
else
0end
from dbo.test
where pwr_1>=
0and pwr_2>pwr_1
select
case
when
sum(pwr)
isnot
null
then
sum(pwr/2)
else
0end
from dbo.test
where pwr_2<=pwr_1
select
case
when
sum(pwr)
isnot
null
then
0else
0end
from dbo.test
where pwr_1<
0
select
(select
case
when
sum(pwr)
isnot
null
then
sum(pwr)
else
0end
from dbo.test
where pwr_1>=
0and pwr_2>pwr_1)+(
select
case
when
sum(pwr)
isnot
null
then
sum(pwr/2)
else
0end
from dbo.test
where pwr_2<=pwr_1)+(
select
case
when
sum(pwr)
isnot
null
then
0else
0end
from dbo.test
where pwr_1<
0)
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