SELECT
   -- here are some columns straight from the subquery and some hardcoded columns like
   'My company' AS CompanyName
   -- and here is the most important part
   SUM(Subq.ImportantFloatWithBigPrecision)
FROM
(
  SELECT
    -- Here are some simple columns fetched from table and after that:
    udf.GetSomeMappedValue(Value) AS MappedValueFromFunction
    ,ImportantFloatWithBigPrecision
  FROM MyVeryBigTable
  WHERE ImportantFloatWithBigPrecision <> 0
    AND(...)
) Subq
GROUP BY everything except SUM(Subq.ImportantFloatWithBigPrecision)
HAVING SUM(Subq.ImportantFloatWithBigPrecision)<>0
ORDER BY (...)