Get Interval Percentage - sql

Question

Please consider this Table:
FileName FileSize
----------------------------
1 33
2 198
3 10
4 127
5 85
6 23
7 105
8 158
9 78
10 90
and I want to create such this result:
FileSize Percentage
--------------------------------
1-50 30%
50-150 50%
150-200 20%
How I can group by and create percentage based on intervals?
Thanks

Answer 1

For a query without bounds table you can create a table inline using VALUES constructor like below
select DISTINCT
CAST(I.LowNumber as VARCHAR) + ' - '+ CAST(I.HighNumber as VARCHAR) as FileSize,
COUNT(*) OVER (PARTITION BY lowNumber,HighNumber ORDER By lowNumber) * 100.00 /COUNT(*) OVER ( ORDER BY (SELECT 1)) as percentage
from TblFile F
join (values (1, 50),(50, 150),(150, 200)) as I(LowNumber, highNumber)
on F.FileSize >=I.LowNumber and F.FileSize<I.HighNumber
Order By I.LowNumber
Your query should look like
select DISTINCT
CAST(I.LowNumber as VARCHAR) + ' - '+ CAST(I.HighNumber as VARCHAR) as FileSize,
COUNT(*) OVER (PARTITION BY lowNumber,HighNumber ORDER By lowNumber) * 100.00 /COUNT(*) OVER ( ORDER BY (SELECT 1)) as percentage
from TblFile F
join TblInterval I
on F.FileSize >=I.LowNumber and F.FileSize<I.HighNumber
Explanation:
Ideally you should leverage set based approach and store the range values in a table. This allows for faster processing and also allows you a single place to limits externally and not in the procedure. This is also in line with Dependency injection principle.
For inline anonymous tables use VALUES constructor. More on this at this msdn link
PS: Insert scripts for table
--create table tblInterval (LowNumber Int, HighNumber Int)
--insert into tblInterval values
--(1,50),(50,150),(150,200)
create table tblFile (fileName int,fileSize int)
insert into tblFile values
( 1 ,33)
,( 2 ,198 )
,( 3 ,10 )
,( 4 ,127 )
,( 5 ,85 )
,( 6 ,23 )
,( 7 ,105 )
,( 8 ,158 )
,( 9 ,78 )
,( 10,90 )
Assuming you have a table like below
TblInterval
LowNumber HighNumber
1 50
50 150
150 200

Answer 2

You can use case statement to make the file size range then get percentage by the count like this
select a.range as FileSize, (Count(*)* 100 / (Select Count(*) From MyTable)) as Percentage
from (
select case
when FileSize between 1 and 50 then '1-50'
when FileSize between 50 and 150 then '50-150'
when FileSize between 150 and 200 then '150-200' end as range
from MyTable) a
group by a.range

Answer 3

CREATE TABLE #A
(
FILENAME INT, FILESIZE INT
)
INSERT INTO #A VALUES
(1,33),
(2,198),
(3,10),
(4,127),
(5,85),
(6,23),
(7,105),
(8,158),
(9,78),
(10,90)
SELECT RANGE,COUNT(*)*100/(SELECT COUNT(*) FROM #A) AS PERCENTAGE
FROM (
SELECT *,CASE
WHEN FILESIZE BETWEEN 1 AND 50 THEN '1-50'
WHEN FILESIZE BETWEEN 50 AND 150 THEN '50-150'
WHEN FILESIZE BETWEEN 150 AND 200 THEN '150-200' END AS RANGE
FROM #A) A
GROUP BY A.RANGE
ORDER BY CASE WHEN RANGE = '1-50' THEN 1
WHEN RANGE ='50-150' THEN 2
WHEN RANGE ='150-200' THEN 3
END
output
RANGE PERCENTAGE
1-50 30
50-150 50
150-200 20

Answer 4

You can use AVG together with partition by:
select distinct
case
when FileSize between 1 and 50 then '1-50'
when FileSize between 50 and 150 then '50-150'
when FileSize between 150 and 200 then '150-200' end as range
, avg(FileSize) OVER (PARTITION BY (select
case when filesize between 0 and 50 then 1
when filesize between 50 and 150 then 2
when filesize between 150 and 200 then 3
end)) as percentage
from mytable