Løsning 1:
SELECT t1.* FROM your_table t1
JOIN (
SELECT MIN(value) AS min_value, dealer
FROM your_table
GROUP BY dealer
) AS t2 ON t1.dealer = t2.dealer AND t1.value = t2.min_value
Løsning 2:
SELECT t1.* FROM your_table t1
LEFT JOIN your_table t2
ON t1.dealer = t2.dealer AND t1.value > t2.value
WHERE t2.value IS NULL
Dette problem er meget berømt, så der er en særlig side til dette i Mysqls manual.
Tjek dette:Rækker med gruppemæssigt maksimum/minimum for en bestemt kolonne