php - 我运行什么查询来为 SQL 表中的每组值选择最高值？

Question

我有一张出价表(例如 eBay 出价):

bid_id | bid_from_user | bid_for_auction | bid_price
1      | 150           | 1               | 20
2      | 453           | 1               | 30
3      | 42            | 1               | 50
4      | 12            | 2               | 12
5      | 60            | 2               | 20

我只需要选择每个bid_for_auction一次当前的最高出价，所以我的结果应该是这样的:

bid_for_auction | bid_price
1               | 50
2               | 20

我该怎么做？

Answer 1

使用GROUP BY

SELECT bid_for_auction, MAX(bid_price) AS bid_price
FROM bids GROUP BY bid_for_auction;