Rounding down decimal numbers in SQL Server 2008

Question

I read all rounding functions of T-SQL like Round, Floor, and Ceil, but none of them has rounded down decimal numbers correctly for me

Answer 1

As per @J0e3gan 's anwser, Sql Server's Round allows rounding to the nearest powers of 10 using the length parameter, where length is 10^(-length), e.g.

length = 0 : 10 ^ 0 = nearest 1
length = 3 : 10 ^ -3 = nearest .001
length = -3 : 10 ^ 3 = nearest 1000

etc

However, in general, with a simple 1-based rounding function - e.g. (Sql Round with Length=0) to round to an arbitrary value of "nearest N" - with the formula:

round(X / N) * N

e.g. nearest 100

select round(12345 / 100.0, 0) * 100.0 -- 12300
select round(-9876 / 100.0, 0) * 100.0 -- -9900
select round(-9849 / 100.0, 0) * 100.0 -- -9800

... Nearest 0.5

select round(5.123 / 0.5, 0) * 0.5 -- 5.000
select round(6.499 / 0.5, 0) * 0.5 -- 6.500
select round(-4.499 / 0.5, 0) * 0.5 -- -4.50

... Nearest 0.02

select round(5.123 / .02, 0) * .02 -- 5.12
select round(-9.871 / .02, 0) * .02 -- -9.88

etc

Remember that the type used for the divisors must be numeric / decimal or float.