选择使用MAX和GROUP BY的所有相应的字段

Question

我有这样的表：

和我想作，将返回每个请求deal_id具有最高timestamp的行，并相应status_id

因此，对于这个例子，我将返回2行：

1226, 3, 2009-08-18 12:10:25
1227, 2, 2009-08-17 14:31:25

我试图与此查询做

SELECT deal_id, status_id, max(timestamp) FROM deal_status GROUP BY deal_id

但它会返回错误status_id：

1226, 1, 2009-08-18 12:10:25
1227, 1, 2009-08-17 14:31:25

Answer 1

没有一个单一的主键字段，我认为最好的办法是：

select * from deal_status
inner join
  (select deal_id as did, max(timestamp) as ts
  from deal_status group by deal_id) as ds
  on deal_status.deal_id = ds.did and deal_status.timestamp = ds.ts

这如果允许其在同一时间同一产品两种不同的状态仍然无法工作

Answer 2

嗨，我希望这给ü希望它

select deal_id,status_id, timestamp from deal_status 
inner join
  (select deal_id as did,max(timestamp) as ts
  from deal_status group by deal_id  )as ds
  on deal_status.deal_id = ds.did and deal_status.timestamp = ds.ts order by deal_id