[sql] How to do a SUM() inside a case statement in SQL server

I want to add some calculation inside my case statement to dynamically create the contents of a new column but I get the error:

Column 'Test1.qrank' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

This is the code I'm working on

case 
    when test1.TotalType = 'Average' then Test2.avgscore
    when test1.TotalType = 'PercentOfTot' then (cnt/SUM(test1.qrank))
    else cnt
end as displayscore

I did try to group but it didn't work.

Any hints?

If you're using SQL Server 2005 or above, you can use the windowing function SUM() OVER ().

case 
when test1.TotalType = 'Average' then Test2.avgscore
when test1.TotalType = 'PercentOfTot' then (cnt/SUM(test1.qrank) over ())
else cnt
end as displayscore

But it'll be better if you show your full query to get context of what you actually need.

You could use a Common Table Expression to create the SUM first, join it to the table, and then use the WHEN to to get the value from the CTE or the original table as necessary.

WITH PercentageOfTotal (Id, Percentage) 
AS 
(
    SELECT Id, (cnt / SUM(AreaId)) FROM dbo.MyTable GROUP BY Id
)
SELECT 
    CASE
        WHEN o.TotalType = 'Average' THEN r.avgscore
        WHEN o.TotalType = 'PercentOfTot' THEN pt.Percentage
        ELSE o.cnt
    END AS [displayscore]
FROM PercentageOfTotal pt
    JOIN dbo.MyTable t ON pt.Id = t.Id

The error you posted can happen when you're using a clause in the GROUP BY statement without including it in the select.

Example

This one works!

     SELECT t.device,
            SUM(case when transits.direction = 1 then 1 else 0 end) ,
            SUM(case when transits.direction = 0 then 1 else 0 end) from t1 t 
            where t.device in ('A','B') group by t.device

This one not (omitted t.device from the select)

     SELECT 
            SUM(case when transits.direction = 1 then 1 else 0 end) ,
            SUM(case when transits.direction = 0 then 1 else 0 end) from t1 t 
            where t.device in ('A','B') group by t.device

This will produce your error complaining that I'm grouping for something that is not included in the select

Please, provide all the query to get more support.