How to select top 1 record per group

抓取客戶最後一次購買此產品的日期


SELECT   product, cus, date
FROM      (
                 SELECT   product,
                                   cus,
                                   date,
                                   row_number() over (partition by product, cus order by date desc) as ranker
                 FROM      SalesTable
                 ) z
WHERE   ranker = 1