判断语句怎摸写？
select (case a.delaytime when datediff(dd,endtime,completetime)> 0 then abs(datediff(dd,endtime,completetime)
end ) DelayTime
from projectinfo a
实现功能：如果实际交货日期大于计划交货日期，则相减，得到延期天数
在查询分析器里用出错，不知是哪里问题？
[解决办法]
select id, sum(case when datediff(dd,endtime,completetime)> 0 then abs(datediff(dd,endtime,completetime)
end ) DelayTime
from projectinfo a
group by id
[解决办法]
select (case when datediff(dd,endtime,completetime)> 0 then abs(datediff(dd,endtime,completetime) else a.delaytime
end ) DelayTime
from projectinfo a
[解决办法]
-try
select case when datediff(dd,endtime,completetime)> 0 then abs(datediff(dd,endtime,completetime)
end ) DelayTime
from projectinfo a
[解决办法]
--ok
select case when datediff(dd,endtime,completetime)> 0 then abs(datediff(dd,endtime,completetime)) end DelayTime from projectinfo a
[解决办法]
select DelayTime = case datediff(dd,endtime,completetime) when > 0 then abs(datediff(dd,endtime,completetime)
end ) DelayTime
from projectinfo a
[解决办法]
select case when datediff(dd,endtime,completetime)> 0 then abs(datediff(dd,endtime,completetime)) end DelayTime from projectinfo a
