how to calculate percent of total within group by statement?

Question

I have a table with 1 record per sale per salesperson per day

NAME  DATE
joe   1-1-13
joe   1-1-13
joe   1-1-13
dave  1-1-13
joe   1-2-13

I

Answer 1

Use a nested query to get the daily total:

BEGIN

    create table #sales (name varchar(10), salesdate date )

    insert into #sales (name, salesdate) values 
        ('joe', '01-01-2013'), 
        ('joe', '01-01-2013'), 
        ('joe', '01-01-2013'), 
        ('dave', '01-01-2013'),  
        ('joe', '01-02-2013'),
        ('dave', '01-02-2013')

    SELECT name, salesdate, COUNT(*) AS personDailyTotal, MAX(dailyTotal) AS dailyTotal, 
        (COUNT(*) * 100.0) / MAX(dailyTotal) AS [Percent]
    FROM #sales
    INNER JOIN (
        SELECT salesdate as [day], COUNT(*) as dailyTotal 
        FROM #sales 
        GROUP BY salesdate
    ) AS [Total] ON salesdate = [day]
    GROUP BY name, salesdate

END

Answer 2

Not the most elegant way to do it, but you can try this -

select [name],[salesdate], COUNT(*) as dayTotal, 
SUM(COUNT(*)) over() as AllSales, 
(COUNT(*) * 1.0) / SUM(COUNT(*)) over() as dayPercent
FROM [dbo].[sales]
group by [name], [salesdate]

I removed the # in your table name. Btw, this code depends on OVER() clause. You can find out how to truncate the excess zeros yourself.

name    salesdate   dayTotal    AllSales    dayPercent
dave    2013-01-01  1           5           0.200000000000
joe   2013-01-01    3           5           0.600000000000
joe   2013-01-02    1           5           0.200000000000

HTH.

If that query looks too complicated to you, then look at this one first. It will give you an idea of what I am trying to do.

select [name],[salesdate], COUNT(*) as dayTotal, 
SUM(COUNT(*)) over() as AllSales
FROM [dbo].[sales]
group by [name], [salesdate]

Answer 3

-- Use Below Query

select T1.salesdate, name ,convert(numeric(18,2),convert(decimal,count(*)) * 100 / T2.total) as percentage from #sales T1
     inner join (
     select salesdate,count(*) as total from #sales group by salesdate
     ) as T2
     on T1.salesdate = T2.salesdate
     group by name,T1.salesdate,T2.total

Answer 4

The most upvoted answer doesn't seem correct.

The OP has the expected answer

for example on 1-1-13 Joe sold 3 units out of 4 total for the day (75%)

and yet the upvoted answer shows 60%.

Instead of summing over all data it should be partitioned by day, here's a better example:

select [name],[salesdate], COUNT(*) as dayTotal, 
SUM(COUNT(*)) over(PARTITION BY salesdate) as AllDaySales, 
(COUNT(*) * 1.0) / SUM(COUNT(*)) over(PARTITION BY salesdate) as dayPercent
FROM [dbo].[sales]
group by [name], [salesdate]