sql-server - 如何为每个 DetailId 选择具有更大 CreateDate 的 FlowId

Question

如何为每个 [DetailId] 选择具有更大 [CreateDate] 的 [FlowId] 例如详细信息数据

Answer 1

尝试这个

select * from t a
where dt = (select max(dt)
            from T b where a.detailid = b.detailid)
order by 1

SQL 演示

Answer 2

假设 SQL Server 2005 及更高版本，请使用ROW_NUMBER 之类的排名函数：

with TopFlow as
(
  select *
    , FlowRank = row_number() over (partition by DetailID
                                   order by [Date] desc, FlowID desc)
  from MyTable
)
select DetailID
  , FlowID
  , [Date]
from TopFlow
where FlowRank = 1

SQL Fiddle 与演示。

Answer 3

select M.*
from MyTable M
inner join 
(
select DetailID,max(Date) Date
from MyTable
Group by DetailID
)T
on M.DetailID=T.DetailID
and M.Date=T.Date
order by M.DetailID

SQL小提琴