phan phan - 7 months ago 38
SQL Question

How do I count decimal places in SQL?

I have a column X which is full of floats with decimals places ranging from 0 (no decimals) to 6 (maximum). I can count on the fact that there are no floats with greater than 6 decimal places. Given that, how do I make a new column such that it tells me how many digits come after the decimal?

I have seen some threads suggesting that I use CAST to convert the float to a string, then parse the string to count the length of the string that comes after the decimal. Is this the best way to go?


You can use something like this:

declare @v sql_variant

set @v=0.1242311

select SQL_VARIANT_PROPERTY(@v, 'Scale') as Scale

This will return 7.

I tried to make the above query work with a float column but couldn't get it working as expected. It only works with a sql_variant column as you can see here:!6/5c62c/2

So, I proceeded to find another way and building upon this answer, I got this:

SELECT value,
                      CONVERT(VARCHAR(50), value, 128)
                     ) AS float
             ) AS bigint
   ) as Decimals
FROM Numbers

Here's a SQL Fiddle to test this out:!6/23d4f/29

To account for that little quirk, here's a modified version that will handle the case when the float value has no decimal part:

SELECT value,
       Decimals = CASE Charindex('.', value)
                    WHEN 0 THEN 0
           Len (
              Reverse(CONVERT(VARCHAR(50), value, 128)) AS FLOAT
                 ) AS BIGINT
FROM   numbers

Here's the accompanying SQL Fiddle:!6/10d54/11