SQL: Order By dictated by a different table

Hopefully very simple SQL question - I'm just b开发者_开发知识库lacking out :)

I have a table of vendors (id, name, description, url). It used to be the web service returned them all sorted by id. After a while, I was asked to return sorted by name. Now they want me to allow them to change the order manually - to showcase new vendors.

Suppose I create another table, VendorOrder with (vendorid, placement), what can I put in the Order By section of the original query, to return the vendors sorted by placement?

As always, thanks in advance.

Guy

---

select 
  vendor.id,
  vendor.name,
  vendor.description,
  vendor.url
from 
  vendors,
  vendorOrder
where
  vendors.id = vendorOrder.vendorId
order by 
  vendorOrder.placement;

Make sure that you find exactly one vendorId in vendorOrder for each id in vendor, otherwise use a left join between the tables.