SQL Server - Top Saleperson Per Region

Question

    SELECT region, person, sum(dollars) as thousands
    FROM sales
    GROUP BY region, person
    ORDER BY region, sum(dollars) desc

The SQL above produces a complete list of sales people per region like this

    region person      thousands

    canada mike smith  $114
    canada joe blog    $76
    canada pete dodd   $45
    usa    john doe    $253
    usa    jane smyth  $120
    europe pieter tsu  $546
    europ  mike lee    $520

If I'm only interested in showing the top salesperson per region (as below), how can I best do that?

    region person      thousands

    canada mike smith  $114
    usa    john doe    $253
    europe pieter tsu  $546

Answer 1

I've done something like burnall suggested. I wasn't getting much love with the "top 1 with ties" part, so I made the whole thing a subquery and chose rows where ranking = 1.

select *
from
(
     select region, 
            person, 
            rank() over(partition by region order by sum(dollars) desc) as ranking
     from sales 
     group by region, 
              person 

) temp
where ranking = 1

Note that this also works for ties since rank() seems to place the same ranking on sums that are equal.