Need help with SQL aggregation query

Question

What is the most straightforward approach to producing a data set that can be used in a SQL Server Reporting Services report to display the following:

SalesPerson        # Sales        # Gross        Profit
John Doe               100       $140,000       $25,000
Everyone Else (Avg.)  1200     $2,000,000      $250,000


Jane Smith              80       $100,000       $15,000
Everyone Else (Avg.)  1220     $2,040,000      $260,000


...and so on.

This is a very, very simplified example of what I'm trying to do (for instance, the real scenario involves showing the 'Everyone Else' broken out into three categorical rows), but it illustrates the primary objective of displaying aggregate data for each individual with a comparison to everyone else (exclusive). Pseudo-code would be fine. My first stab at the SQL code for this got pretty tangled pretty quickly, and I know there must be a more direct method.

Any tips appreciated.

Answer 1

If you do not mind formatting later, then if we assume you have something like:

First I'll need some helper variables for total counts

/* Few helper variables*/
DECLARE @TotalQuantity int
       ,@TotalAmount decimal(19, 4)
       ,@TotalProfit decimal(19, 4)
       ,@EveryoneElse int

Then we fetch total for everyone in a given period (YEAR = 2009)

/* Fetch totals in the period*/
SELECT  @TotalQuantity = sum(SalesQuantity)
       ,@TotalAmount = sum(SalesAmount)
       ,@TotalProfit = sum(Profit)
       ,@EveryoneElse = count(DISTINCT SalesPersonKey) - 1
FROM   factSales AS s
       JOIN dimDate AS d ON s.DateKey = d.DateKey
WHERE   [Year] = 2009

/* Now we have totals for everyone in the period */

And now for each person vs everyone else, but all in one row.

/* Totals for each sales person vs everyone else Average */
SELECT  FullName
       ,SUM(SalesQuantity) AS [PersonSalesCount]
       ,SUM(SalesAmount) AS [PersonSalesAmount]
       ,SUM(Profit) AS [PersonSalesProfit]
       ,( @TotalQuantity - SUM(SalesQuantity) ) / @EveryoneElse AS [EveryoneElseAvgSalesCount]
       ,( @TotalAmount - SUM(SalesAmount) ) / @EveryoneElse AS [EveryoneElseAvgSalesAmount]
       ,( @TotalProfit - SUM(Profit) ) / @EveryoneElse AS [EveryoneElseAvgSalesProfit]
FROM    factSales AS s
        JOIN dimDate AS d ON s.DateKey = d.DateKey
        RIGHT JOIN dimSalesPerson AS p ON p.SalesPersonKey = s.SalesPersonKey
WHERE   [Year] = 2009
GROUP BY FullName

Now you can package all this in a stored procedure with parameter(s) for date interval. May still need to tweak number of sales people to determine which were active in a certain period and how to count those who did not sell anything. With this, EveryoneElse means number of sales people who sold something -1; so if you have 10 sales people and only 5 sold something, than EveryoneElse = 4.