5/19/2013

Select the higest total in each group.

SELECT MIN(x.id),  -- change to MAX if you want the highest

          x.customer,

          x.total

FROM PURCHASES x

JOIN (SELECT p.customer,

          MAX(total) AS max_total

          FROM PURCHASES p

          GROUP BY p.customer) y ON y.customer = x.customer

           AND y.max_total = x.total

GROUP BY x.customer, x.total