USE AdventureWorks2012;
GO
SELECT p.FirstName, p.LastName
 ,ROW_NUMBER() OVER (ORDER BY a.PostalCode) AS "Row Number"
 ,RANK() OVER (ORDER BY a.PostalCode) AS Rank
 ,DENSE_RANK() OVER (ORDER BY a.PostalCode) AS "Dense Rank"
 ,NTILE(4) OVER (ORDER BY a.PostalCode) AS Quartile
 ,s.SalesYTD
 ,a.PostalCode
FROM Sales.SalesPerson AS s
 INNER JOIN Person.Person AS p
 ON s.BusinessEntityID = p.BusinessEntityID
 INNER JOIN Person.Address AS a
 ON a.AddressID = p.BusinessEntityID
WHERE TerritoryID IS NOT NULL AND SalesYTD <> 0;
In the query above, I want to know how do I calculate the head count, as in How many people stay in the same Postal Code area?