SQL每个商品销量最高的日期

表：order_detail
字段：sku_id（商品ID）,create_date（下单日期）,sku_num（商品购买数量）,sku_amount（商品购买金额）

需求：每个商品销量最高的日期

select sku_id,create_date,total_num from (
    select sku_id,create_date,total_num,dense_rank() over(partition by sku_id order by total_num desc) rt from (
    select sku_id,create_date,sum(sku_num) total_num from order_detail group by sku_id,create_date
    ) a 
) b where  rt = 1