Re: How does group by algorithm works?

[Rick James]

But, you can make it work with some extra effort:

select item, supplier, price as cheapest_price
   from (
      select item, supplier, price
         from products
         order by item asc, price asc
        )
   group by item ;

This is because the value of 'supplier' is not really arbitrary; it is actually the 'first' value found. Hence, you have to put the ORDER BY in the inner query, and let the ordering deal with the MIN().