Question

I need to run a huge query with the option to sum up one column. I’m wondering if it would be possible to do something like the following:

declare @sumIt bit
set @sumIt = 1

select ID, Name, CASE WHEN @sumIt=1 THEN sum(Time) ELSE Time END [timeCol]     
from Visits
where ID = 123
Group by ID, Name, CASE WHEN @sumIt=1 THEN '' ELSE Time END

Right now I get an error:
Msg 8120, Level 16, State 1, Line 4
Column ‘Visits.Time’ is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

Answer 1

I think you can do the following:

declare @sumIt bit
set @sumIt = 1

select ID, Name,
       (CASE WHEN @sumIt=1 THEN sum(Time) ELSE min(Time) END) [timeCol]
from Visits
where ID = 123
Group by ID, Name, (CASE WHEN @sumIt=1 THEN '' ELSE Time END) 

You can apply an aggregation function to the group by variables. This isn’t commonly done, but it solves your problem.