Use CASE statement with SUM function in SQL Server

问题

I am working on SQL Server 2008 R2. I am trying to get the sum.

This is my query

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

When I execute it give me following error.

Msg 130, Level 15, State 1, Line 3
Cannot perform an aggregate function on an expression containing an aggregate or a sub query.

I know I am using sum function with case clause. But I need to find sum with this case statement.

回答1:

Indeed; that case is per row, since you don't have a group; SUM(quantity) is largely meaningless when referring to a single row. If that is the SUM over the entire set, you will have to compute that first into a variable. Otherwise you'll need to think about what group / partition you intended that inner-SUM to apply to.

To give a similar example:

This works:

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

and this works:

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

but this does not:

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

likewise, this works:

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

but this does not, giving the same error message that you report:

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

回答2:

not sure what sec is in this case but i would take this and create a derived table

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

query above probably will not work off the bat as there is not much information to work with

Answer above explains why the query is not working much better than mine

来源：https://stackoverflow.com/questions/17612387/use-case-statement-with-sum-function-in-sql-server

标签

sql

sql-server

sql-server-2008-r2