Question

是否可以使用窗口函数进行累加乘法（低于查询）

    select Id, Qty
    into #temp
    from(
            select 1 Id, 5 Qty 

            union   

            select 2, 6

            union   

            select 3, 3
    )dvt

    select 
    t1.Id
    ,exp(sum(log( t2.Qty))) CumulativeMultiply
    from #temp t1
    inner join #temp t2 
        on t2.Id <= t1.Id
    group 
    by t1.Id
    order 
    by t1.Id

像：

select 
        t1.Id
        ,exp(sum(log( t2.Qty))) over (partition by t1.Id order by t1.Id rows between unbounded preceding and current row )  CumulativeMultiply
        from #temp t1
        inner join #temp t2 
            on t2.Id <= t1.Id

但是得到错误：

功能＆＃39; exp＆＃39;不是有效的窗口函数，不能与OVER子句
一起使用

更新实际上我想要的结果：

Id          CumulativeMultiply
----------- ----------------------
1           5
2           30
3           90

Answer 1

Sum Over(Order by)无需自联接以查找以前的记录并将其相乘

 select  
        Id
        ,exp(sum(log( Qty))
        over (order by Id )) CumulativeMultiply from #temp

Answer 2

只有聚合函数才是有效的窗口函数。

我没有测试代码，但你需要以某种方式分离2：

SELECT Id, exp(cm) CumulativeMultiply
FROM (
select 
        Id
        ,sum(log(Qty)) over (partition by Id order by Id rows between unbounded preceding and current row )  cm
        from #temp
) d

使用窗口函数的累积乘法，＆＃39; exp＆＃39;不是有效的窗口函数

2 个答案: