MySQL：按组内排序

我有一个mysql表，如下所示：

mysql> select * from pt_onhand where pn = '000A569011';
+------------+-----+----+--------+------------+---------+--------------+-----+
| pn         | pa  | mn | ACTIVE | locate     | onhand  | avg_cost     | whs |
+------------+-----+----+--------+------------+---------+--------------+-----+
| 000A569011 | P/A |    |        | AA-112     | 13.0000 | 0.0000000000|     |
| 000A569011 | P/A |    |        | PF120136.1 |  1.0000 | 5.4785156200 |     |
+------------+-----+----+--------+------------+---------+--------------+-----+

mysql> select sum(onhand),max(locate),avg_cost from pt_onhand where pn = '000A569011' group by pn;
+-------------+-------------+--------------+
| sum(onhand) | max(locate) | avg_cost     |
+-------------+-------------+--------------+
|     14.0000 | PF120136.1  | 0.0000000000|
+-------------+-------------+--------------+

我想执行如下查询：

mysql> select * from pt_onhand where pn = '000A569011';
+------------+-----+----+--------+------------+---------+--------------+-----+
| pn         | pa  | mn | ACTIVE | locate     | onhand  | avg_cost     | whs |
+------------+-----+----+--------+------------+---------+--------------+-----+
| 000A569011 | P/A |    |        | AA-112     | 13.0000 | 0.0000000000|     |
| 000A569011 | P/A |    |        | PF120136.1 |  1.0000 | 5.4785156200 |     |
+------------+-----+----+--------+------------+---------+--------------+-----+

mysql> select sum(onhand),max(locate),avg_cost from pt_onhand where pn = '000A569011' group by pn;
+-------------+-------------+--------------+
| sum(onhand) | max(locate) | avg_cost     |
+-------------+-------------+--------------+
|     14.0000 | PF120136.1  | 0.0000000000|
+-------------+-------------+--------------+

---

所以我的问题是：我能在同一个查询中得到与最大（定位）PF120136.1相关的平均成本5.4785156200吗，如何得到？谢谢

虽然有点小麻烦，但它应该可以做到：

select a.onhand, a.locate, p.avg_cost
from
    (select sum(onhand) onhand, max(locate) locate from pt_onhand where pn = '000A569011' group by pn) a
    join pt_onhand p on p.locate = a.locate

---

您还可以执行以下子查询：

select 
     sum(onhand)
    ,max(locate)
    ,(select avg_cost from pt_onhand where pn = pt.pn and locate = max(pt.locate)) as avg_cost 
from 
    pt_onhand pt 
where 
    pn = '000A569011' 
group by pn;

---

但是，根据数据库的大小，可能无法很好地执行，请全部尝试，看看哪个最适合您

您将不得不编写额外的内部查询。然而令人失望。这在sqlite中可以正常工作，甚至可能不会在其他dbms中编译。因为这个原因，我不喜欢mysql