解决方案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

解决方案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

这个问题非常有名，因此在Mysql的手册中有专门的页面。

请检查以下内容： 行包含某列的分组最大/最小值