Question

I have a database with tables:

suppliers:
 fid , name
   1 | 'Andrey' 
   2 | 'lucas'

products:
 pid , name
   1 | 'X' 
   2 | 'Y' 

prdtFrn:
 pid , fid , price
  ---------------- supplier 'andrey'
   1 |  1  | 19.00 
   2 |  1  | 16.00 
  ----------------- supplier 'lucas'
   1 |  2  | 14.00 
   2 |  2  | 18.00 

Querying the products, I get all products that have registred, but I need know who sells current product of ‘product table’ as lowest price, I don’t know how to write the query

Answer 1

select p.* 
from (
    select pid, min(price) as MinPrice
    from prdtFrn
    group by pid
) pm
inner join prdtFrn p on pm.pid = p.pid and pm.MinPrice = p.price

You will see multiple rows per product where two suppliers are selling a product at the same price.