SQL Server中带SUM函数的用例语句

我正在使用SQLServer2008R2。我正在设法算出总数

这是我的问题

select  
  SUM(
    case 
      when sec.SecurityTypeID =  2 then SUM(quantity)*(sec.AnnualIncomeRate/100) 
      when sec.SecurityTypeID = 5 then 0 
      when sec.SecurityTypeID = 11 then SUM(quantity)*sec.AnnualIncomeRate    
      else SUM(quantity)*sec.AnnualIncomeRate   
    end
  ) AS ProjectedIncome 
from Transactions as t

当我执行它时，给我以下错误

味精130，第15级，状态1，第3行
无法对包含聚合或子查询的表达式执行聚合函数

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我知道我使用的是带有case子句的和函数。但我需要找到这个案例陈述的总结；

案例

是每行的，因为您没有

组

<代码>总和（数量）在引用单行时基本上没有意义。如果这是整个集合的

和

，则必须首先将其计算为一个变量。否则，您需要考虑您希望内部-

SUM

应用于哪个组/分区

举一个类似的例子：

这项工作：

select 1 as [a], 2 as [b], 3 as [c]

select case [a] when 1 then [b] else [c] end from (
  select 1 as [a], 2 as [b], 3 as [c]
) x

select sum(case [a] when 1 then [b] else [c] end) from (
  select 1 as [a], 2 as [b], 3 as [c]
) x

这是有效的：

select 1 as [a], 2 as [b], 3 as [c]

select case [a] when 1 then [b] else [c] end from (
  select 1 as [a], 2 as [b], 3 as [c]
) x

select sum(case [a] when 1 then [b] else [c] end) from (
  select 1 as [a], 2 as [b], 3 as [c]
) x

但这并不是：

select case [a] when 1 then sum([b]) else [c] end from (
  select 1 as [a], 2 as [b], 3 as [c]
) x

类似地，这也适用于：

select 1 as [a], 2 as [b], 3 as [c]

select case [a] when 1 then [b] else [c] end from (
  select 1 as [a], 2 as [b], 3 as [c]
) x

select sum(case [a] when 1 then [b] else [c] end) from (
  select 1 as [a], 2 as [b], 3 as [c]
) x

但事实并非如此，它会给出与您报告的相同的错误消息：

select sum(case [a] when 1 then sum([b]) else [c] end) from (
  select 1 as [a], 2 as [b], 3 as [c]
) x

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不确定本例中的sec是什么，但我将使用它并创建一个派生表

select SUM(t.caseValue) AS ProjectedIncome 
from (select * , case 
      when sec.SecurityTypeID =  2 then (quantity)*(sec.AnnualIncomeRate/100) 
      when sec.SecurityTypeID = 5 then 0 
      when sec.SecurityTypeID = 11 then (quantity)*sec.AnnualIncomeRate    
      else (quantity)*sec.AnnualIncomeRate   
end as caseValue  from Transactions) as t

上面的查询可能无法立即执行，因为没有太多信息可供处理

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上面的答案解释了为什么查询的效果没有我的好

谢谢你给我更好的理解。目前，我从其他人那里得到了案例查询，所以我感到困惑。但你能让我更好地理解。再次感谢。