Home/ Questions/Q 1019219
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-16T10:58:39+00:00

I’m looking to create a histogram in SQL (which in itself isn’t too tricky),

  • 0

I’m looking to create a histogram in SQL (which in itself isn’t too tricky), but what I’m looking for is a way of splitting the bins so that each bin / band has the same proportion of the data included within.

For example if I have the sample data (the value column) and I want to divide it into 5 bins, I know that I can work out the number of bins by doing something like 

(MAX(Value) - MIN(Value)) / numberofsteps

Will give the groups we see in the band 1 column.

However what I want is for the bands to be calculated so that each band accounts for (100 / n) % of the total where n is the number of bands (so in this case each of the 5 bands would represent 20% of the total data) – which is what is shown in the band 2 column

Value      band 1     band 2
1     | 1 to 2    | 0 to 1
1     | 1 to 2    | 0 to 1
1     | 1 to 2    | 0 to 1
1     | 1 to 2    | 0 to 1
2     | 1 to 2    | 2 to 3
2     | 1 to 2    | 2 to 3
3     | 1 to 2    | 2 to 3
3     | 1 to 2    | 2 to 3
4     | 3 to 4    | 4 to 6
4     | 3 to 4    | 4 to 6
5     | 5 to 6    | 4 to 6
6     | 5 to 6    | 4 to 6
7     | 7 to 8    | 7 to 8
8     | 7 to 8    | 7 to 8
8     | 7 to 8    | 7 to 8
8     | 7 to 8    | 7 to 8
9     | 9 to 10   | 9 to 10
10    | 9 to 10   | 9 to 10
10    | 9 to 10   | 9 to 10
10  |    9 to 10   | 9 to 10

Is there a way to do this in SQL (i’m using SQL server 2005 if that helps), possibly without creating a UDF and having it so that I can easily alter the number of bins would be great (if that’s not asking the impossible!)

Thanks

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    To divide into bins you can use the ntile function.

    with Vals AS
(
SELECT 1 AS value UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 8 UNION ALL SELECT 8 UNION ALL SELECT 9 UNION ALL SELECT 10 UNION ALL SELECT 10 UNION ALL SELECT 10
), TiledVals AS
(
SELECT value, NTILE(5) OVER (ORDER BY value) AS BinNumber
FROM Vals
)
SELECT value, BinNumber, 
Min(value) OVER (PARTITION BY BinNumber) As StartBin,
 MAX(value) OVER (PARTITION BY BinNumber) As EndBin
FROM TiledVals

    Gives

    value       BinNumber            StartBin    EndBin
----------- -------------------- ----------- -----------
1           1                    1           1
1           1                    1           1
1           1                    1           1
1           1                    1           1
2           2                    2           3
2           2                    2           3
3           2                    2           3
3           2                    2           3
4           3                    4           6
4           3                    4           6
5           3                    4           6
6           3                    4           6
7           4                    7           8
8           4                    7           8
8           4                    7           8
8           4                    7           8
9           5                    9           10
10          5                    9           10
10          5                    9           10
10          5                    9           10
    • 0