Trouble with sums and a having clause - tsql

Question

I have a query that populates a report of "written off" hours, the total of which is the sum RegHrs, OvtHrs, and SpecialOvtHrs, but only those values with a positive value (each of these fields may have positive and negative values - positive values are "written off").
The query I am using (which doesn't work) is:
select
LD.Employee,
max(EM.LastName + ', ' + Em.FirstName) as EMName,
LD.WBS1, LD.WBS2,
sum(LD.RegHrs + LD.OvtHrs + LD.SpecialOvtHrs) as [Hours],
CL.Name as ClientName, pctf.CustProgram,
max(PR.Name) as ProjName,
LD.PKey, ISNULL(BillingDirectives.Comment, 'None')
from AnvilProd..LD
left join AnvilProd..PR on LD.WBS1 = PR.WBS1 and PR.WBS2 = ' ' and PR.WBS3 = ' '
left join AnvilProd..EM on LD.Employee = EM.Employee
left join AnvilProd..CL on PR.ClientID = CL.ClientID
left join AnvilProd..ProjectCustomTabFields pctf on PR.WBS1 = pctf.WBS1 and pctf.WBS2 = ' ' and pctf.WBS3 = ' '
left join InterfaceDev..BillingDirectives on BillingDirectives.PKey = LD.PKey
where LD.BillStatus = 'X'
and LD.WrittenOffPeriod = #custPeriod
and LD.WBS1 not in (select distinct WBS1 from AnvilProd..BT where FeeBasis = 'L')
and LD.WBS1 not in (select distinct WBS1 from InterfaceDev..CircledHoursReportEliminatedJobs where ActiveStatus = 'Active')
group by pctf.CustProgram, CL.Name, LD.WBS1, LD.WBS2, LD.Employee, BillingDirectives.Comment, LD.PKey
-- having ((sum(LD.RegHrs) > 0) or (sum(LD.OvtHrs) > 0) or (sum(LD.SpecialOvtHrs) > 0))
order by pctf.CustProgram, CL.Name, LD.WBS1, WBS2, EMName
I need to find written off hours for each Employee, WBS1, WBS2 combination.
I have tried a dozen different things with that having clause and cannot get it to give me an accurate result.

Answer 1

Use a case inside the sum():
select blah, blah,
sum(
case when LD.RegHrs > 0 then LD.RegHrs else 0 end +
case when LD.OvtHrs > 0 then LD.OvtHrs else 0 end +
case when LD.SpecialOvtHrs > 0 then LD.SpecialOvtHrs else 0 end
) as [Hours], blah, blah
from blah join blah ...
group by blah, blah
-- no having clause
As a mathematical curiosity, you could also code the sum this way:
sum((LD.RegHrs + abs(LD.RegHrs) +
(LD.OvtHrs + abs(LD.OvtHrs) +
(LD.SpecialOvtHrs + abs(LD.SpecialOvtHrs)) / 2
which although is a bit less readable, it uses less code and may impress your colleagues more :)