Round Natural Numbers to the nearest Power of 10

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Round Natural Numbers to the nearest Power of 10

hkravitz

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May 5, 2017 at 4:51 pm

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Comments posted to this topic are about the item Round Natural Numbers to the nearest Power of 10

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Thomas Franz Hall of Fame Points: 3874 More actions · Answer 1

Why do you not use the build in ROUND function?
It takes three parameters:
- the value
- the rounding length (use negative numbers to round to a power of 10, example for 12345: -1 -> = 12350, -2 -> 12300, -3 = 12000
- optional 0 or 1, while the default 0 rounds, while 1 will cut the numbers off; ROUND(12345, -1, 0) = 12350 while ROUND(12345, -1, 1) = 12340

The only benefit of your function is the easier usage of the direction (up or down), but this could be solved by cutting off the decimals (= rounding down) and adding 10 (or 100 or 1000...) when you want to round up: ROUND(12345, -1, 1) + 10

PS: Bonus points for using an INLINE TABLE VALUE function instead of a scalar function

God is real, unless declared integer.

Luis Cazares SSC Guru Points: 183698 More actions · Answer 2

Your function has a problem when it's used against negative numbers. I wrote an article some time ago about this options which simulate CEILING and FLOOR. You can read it in here: http://www.sqlservercentral.com/articles/T-SQL/145448/
s
Here's a corrected version for your function
CREATE FUNCTION dbo.udf_RoundNearest ( @Number bigint, /*Natural Number*/ @RoundNearest float, /*Power of 10, 10^n , 10,100,1000...*/ @Direction int /* 0-> Down , 1 -> Up */ ) RETURNS TABLE AS RETURN SELECT CASE WHEN @Direction = 0 THEN ROUND(@Number-(.49*@RoundNearest),-LOG10(@RoundNearest)) ELSE ROUND(@Number+(.49*@RoundNearest),-LOG10(@RoundNearest)) END Number GO

Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?

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hkravitz Right there with Babe Points: 759 More actions · Answer 3

Luis Cazares - Tuesday, May 16, 2017 6:27 AM
Your function has a problem when it's used against negative numbers. I wrote an article some time ago about this options which simulate CEILING and FLOOR. You can read it in here: http://www.sqlservercentral.com/articles/T-SQL/145448/
s
Here's a corrected version for your function
CREATE FUNCTION dbo.udf_RoundNearest ( @Number bigint, /*Natural Number*/ @RoundNearest float, /*Power of 10, 10^n , 10,100,1000...*/ @Direction int /* 0-> Down , 1 -> Up */ ) RETURNS TABLE AS RETURN SELECT CASE WHEN @Direction = 0 THEN ROUND(@Number-(.49*@RoundNearest),-LOG10(@RoundNearest)) ELSE ROUND(@Number+(.49*@RoundNearest),-LOG10(@RoundNearest)) END Number GO

Thank you for your input!

hkravitz Right there with Babe Points: 759 More actions · Answer 4

t.franz - Tuesday, May 16, 2017 2:56 AM
Why do you not use the build in ROUND function?
It takes three parameters:
- the value
- the rounding length (use negative numbers to round to a power of 10, example for 12345: -1 -> = 12350, -2 -> 12300, -3 = 12000
- optional 0 or 1, while the default 0 rounds, while 1 will cut the numbers off; ROUND(12345, -1, 0) = 12350 while ROUND(12345, -1, 1) = 12340
The only benefit of your function is the easier usage of the direction (up or down), but this could be solved by cutting off the decimals (= rounding down) and adding 10 (or 100 or 1000...) when you want to round up: ROUND(12345, -1, 1) + 10
PS: Bonus points for using an INLINE TABLE VALUE function instead of a scalar function

Thanks!