Nice function.

Tip 1: Instead of the CASE to get rid of negative values, use ABS.

Tip 2: Add a CASE to work around the domain error you'd get from LOG10(0).

Tip 3: Stop being lazy and use decimal instead of float. Because float can't represent many values exactly, you run the risk of errors. For instance:

SELECT dbo.fix(1.15)   -- Returns 1.1 instead of 1.2

alter

function dbo.fix(@num numeric(36,18), @digits int) returns numeric(36,18) as

begin

declare @res float

select @res = case when @num = 0 then 0

else round(@num,@digits-1-floor(log10(abs(@num)))) end

return (@res)

end