SQL根据条件执行不同的语句

SQL根据条件执行不同的语句

select w.WorkloadID,
p.ProcessName,
F.FlowName,
D.District_Name,
w.AreaCode,
W.SCadastralNumber,
W.ECadastralNumber,
W.WE_Name,
W.W_Name,
W.GroupWork,
W.STime,
W.Days,
W.ETime,
F.FlowName,
F.DayWorks,
W.Days,
W.Days*F.DayWorks as DayWorks,
convert(decimal(18,2),W.GroupWork-(W.Days*F.DayWorks)) as DeductDayW,
case when F.FlowID='-1' then convert(decimal(18,2),W.GroupWork-(W.Days*F.DayWorks)*P.P_Ratio,2) else convert(decimal(18,2),W.GroupWork-(W.Days*F.DayWorks)*F.F_Ratio,2) end as Yield
from Workload W left join District D on W.District_ID=D.District_Num 
Left join Process p on w.ProcessID=p.ProcessID 
left join Flow F on w.FlowID=F.FlowID看看是这个意思吗？
追问对，就是这个意思，谢谢了

case when F.FlowID=‘-1’
then convert(decimal(18,2),W.GroupWork-(W.Days*F.DayWorks)*P.P_Ratio,2) else
when F.FlowID<>‘-1’
convert(decimal(18,2),W.GroupWork-(W.Days*F.DayWorks)*F.F_Ratio,2) end as Yield