SQL内部联接 - 获取最大值

Question

2个与recordKey相关的表:

交易表

TransId   recordKey
44          111
56          234 

历史表

HistoryId   recordKey   ProcessTime
1              111              0
2              111              200
3              111              4000
4              234              10

如何加入此表,以便在分组时,只获得最大处理时间(4000)？

更新:结果将如下所示:

TransId ProcessTime
44 4000
55 10

Answer 1

SELECT   transId, MAX(processTime)
FROM     transaction
JOIN     history ON history.recordKey = transaction.recordKey
GROUP BY transId