SELECT
SalesOrderID,
SalesPersonID,
OrderDate,
ROW_NUMBER() OVER ( PARTITION BY SalesPersonID ORDER BY OrderDate) AS OrderRank FROM Sales.SalesOrderHeader WHERE SalesPersonID IS NOT NULL
SalesOrderID,
SalesPersonID,
OrderDate,
ROW_NUMBER() OVER ( PARTITION BY SalesPersonID ORDER BY OrderDate) AS OrderRank FROM Sales.SalesOrderHeader WHERE SalesPersonID IS NOT NULL