DECLARE @Sales TABLE
(
SalesPersonID varchar(10), TotalSales int
)


INSERT @Sales
SELECT 1, 200 UNION ALL
SELECT 2, 300 UNION ALL
SELECT 7, 300 UNION ALL
SELECT 4, 100 UNION ALL
SELECT 5, 600 UNION ALL
SELECT 5, 600 UNION ALL
SELECT 2, 200 UNION ALL
SELECT 5, 620 UNION ALL
SELECT 4, 611 UNION ALL
SELECT 3, 650 UNION ALL
SELECT 7, 611 UNION ALL
SELECT 9, 650 UNION ALL
SELECT 3, 555 UNION ALL
SELECT 9, 755 UNION ALL
SELECT 8, 650 UNION ALL
SELECT 3, 620 UNION ALL
SELECT 5, 633 UNION ALL
SELECT 6, 720
GO

select top 10 percent SalesPersonID, sum(TotalSales)
  from Sales
 order by sum(TotalSales)
 group by SalesPersonID

select top 10 percent SalesPersonID, sum(TotalSales)
  from Sales
 order by sum(TotalSales) desc
 group by SalesPersonID

--Top 10%
SELECT TOP 10 PERCENT SalesPersonID, SUM(TotalSales) FROM @Sales
GROUP BY SalesPersonID
ORDER BY SUM(TotalSales) ASC

--Bottom 10%
SELECT TOP 10 PERCENT SalesPersonID, SUM(TotalSales) FROM @Sales
GROUP BY SalesPersonID
ORDER BY SUM(TotalSales) DESC

--By Dept
SELECT TOP 10 PERCENT Department, SUM(TotalSales) FROM @Sales
GROUP BY Department
ORDER BY SUM(TotalSales) ASC/DESC //(Whichever one you want)

DECLARE @Sales TABLE (SalesPersonID varchar(10), TotalSales int)INSERT @Sales
SELECT 1, 200 UNION ALL
SELECT 2, 300 UNION ALL
SELECT 7, 300 UNION ALL
SELECT 4, 100 UNION ALL
SELECT 5, 600 UNION ALL
SELECT 5, 600 UNION ALL
SELECT 2, 200 UNION ALL
SELECT 5, 620 UNION ALL
SELECT 4, 611 UNION ALL
SELECT 3, 650 UNION ALL
SELECT 7, 611 UNION ALL
SELECT 9, 650 UNION ALL
SELECT 3, 555 UNION ALL
SELECT 9, 755 UNION ALL
SELECT 8, 650 UNION ALL
SELECT 3, 620 UNION ALL
SELECT 5, 633 UNION ALL
SELECT 6, 720


;with a as
(
    select SalesPersonID, sum(TotalSales) as Total
    from @Sales
    group by SalesPersonID
)
select coalesce(a.SalesPersonID, b.SalesPersonID) as SalesPersonID, coalesce(a.Total,b.Total) as Total
from a a
    full outer join a b
    	on a.SalesPersonID=b.SalesPersonID
where a.SalesPersonID in (select top 10 percent SalesPersonID from a order by Total desc)
    or b.SalesPersonID in (select top 10 percent SalesPersonID from a order by Total)
order by a.Total desc