How to use IF search condition as "true" value - mysql

Question

I am creating a report generator which allows me to build custom reports by selecting tables and fields which are saved in the database. Each table, field, calculated value, etc. is treated as a separate entity, with no direct connection to any other entity. They are all self-contained.
I have a number of count fields/columns, which I currently have working, using code similar to the following:
sum(case when usasf_teams.division_levelid=7 then 1 else 0 end) as Dance
My problem is that there are quite a few of these columns, and most of the values are zero. This makes it hard to spot the non-zero values, which are what we want to see.
I know I can use the IF statement to return either the number or a space, but I don't want to put the server through the work of doing the same operation twice for every column in every row. I would like to do something like this:
if(sum(case when usasf_teams.division_levelid=7 then 1 else 0 end),
{{use the comparison value}}, ' ') as Dance
This way, the sum/case operation is only done once for each field.
Is this possible?

Answer 1

First, you can simplify your logic to:
sum(usasf_teams.division_levelid = 7) as Dance
Then, I would recommend changing the 0 values to NULL rather than a space:
nullif(sum(usasf_teams.division_levelid = 7), 0) as Dance
If you are going to return a real space, you need to be careful of types. You could do this as;
select (case when sum(usasf_teams.division_levelid = 7) > 0
then cast(sum(usasf_teams.division_levelid = 7) as char)
else ' '
end)
You don't need to worry about doing the sum() twice. The expense in an aggregation is manipulating the data, not (in general) calculating the aggregation functions themselves.