sql问题，急

[知道vdsdf]

string sql12=string.Format(@"update Entity_69052 set differencefe=t.chazhi from (
select slotnum
,MAX(CAST(ContentFe AS FLOAT))-MIN(CAST(ContentFe AS FLOAT)) as chazhi
,MAX(ExamineTime) as maxtime from Entity_69052 where ExamineTime<(select Max(ExamineTime) from Entity_69052 where Entity_69051_FK ='{0}')
group by slotnum) t
where Entity_69052.slotnum = t.slotnum and ExamineTime = t.maxtime and t.chazhi is not null",KeyOID);


想求出Entity_69052 中 某一时间与某一时间的ContentFe差，赋值给 differencefe ，可是没有赋值，求解答

[Yole]

select differencefe
 from (
select slotnum
,MAX(CAST(ContentFe AS FLOAT))-MIN(CAST(ContentFe AS FLOAT)) as chazhi
,MAX(ExamineTime) as maxtime from Entity_69052  where ExamineTime<(select Max(ExamineTime) from Entity_69052 where Entity_69051_FK ='{0}')
group by slotnum) t
where Entity_69052.slotnum = t.slotnum and ExamineTime = t.maxtime and t.chazhi is not null

这个语句您能查到值么？查不到的话自然就没法赋值啊。

[知道vdsdf]

引用 1 楼 u010192842 的回复:

select differencefe
 from (
select slotnum
,MAX(CAST(ContentFe AS FLOAT))-MIN(CAST(ContentFe AS FLOAT)) as chazhi
,MAX(ExamineTime) as maxtime from Entity_69052  where ExamineTime<(select Max(ExamineTime) from Entity_69052 where Entity_69051_FK ='{0}')
group by slotnum) t
where Entity_69052.slotnum = t.slotnum and ExamineTime = t.maxtime and t.chazhi is not null

这个语句您能查到值么？查不到的话自然就没法赋值啊。

感谢你回答我的问题，我想问我写的对不对，，，数据库影噶能查到这个数据，我应该是写错了，求改写 [quote=引用 1 楼 u010192842 的回复:]

select differencefe
 from (
select slotnum
,MAX(CAST(ContentFe AS FLOAT))-MIN(CAST(ContentFe AS FLOAT)) as chazhi
,MAX(ExamineTime) as maxtime from Entity_69052  where ExamineTime<(select Max(ExamineTime) from Entity_69052 where Entity_69051_FK ='{0}')
group by slotnum) t
where Entity_69052.slotnum = t.slotnum and ExamineTime = t.maxtime and t.chazhi is not null

这个语句您能查到值么？查不到的话自然就没法赋值啊。[/quote 感谢你回答我的问题，我想问我写的对不对，，，数据库影噶能查到这个数据，我应该是写错了，求改写

[Yole]

update a  set a.differencefe=t.chazhi
from Entity_69052 a,
(
select slotnum
,MAX(CAST(ContentFe AS FLOAT))-MIN(CAST(ContentFe AS FLOAT)) as chazhi
,MAX(ExamineTime) as maxtime from Entity_69052  where ExamineTime<(select Max(ExamineTime) from Entity_69052 where Entity_69051_FK ='{0}')
group by slotnum
) t
where a.slotnum = t.slotnum and a = t.maxtime and t.chazhi is not null

语法上没问题~不知道数据是啥样的