sql - What are the products of each categories fewest requested by customers? NorthwindDB -

i have tried solve question , got this

select      c.categoryid, p.productid,p.productname, count(orderid) totalv       [order details] od inner join      products p on od.productid = p.productid inner join      categories c on c.categoryid = p.categoryid inner join      (select           t.categoryid, min(totalv) minv                (select                categories.categoryid, products.productid,                count(orderid) totalv                           [order details]           join                products on [order details].productid = products.productid           join                categories on categories.categoryid = products.categoryid           group                products.productid, categories.categoryid) t     group          t.categoryid) n on c.categoryid = n.categoryid group      c.categoryid, p.productid, minv, p.productname having      count(orderid) = minv 

results :

categoryid | productid |        productname         | totalv -----------| ----------| ---------------------------| ------  1          | 67        | laughing lumberjack lager  | 10      2          | 15        | genen shouyu               | 6 3          | 48        | chocolade                  | 6 .            .                   .                     . .            .                   .                     . .            .                   .                     . 

i'm not sure if way because i'm using twice this:

select      categories.categoryid,products.productid, count(orderid) totalv       [order details] join      products on [order details].productid = products.productid join      categories on categories.categoryid = products.categoryid group      products.productid, categories.categoryid 

so think there better way perform question, help?