SQL内部联接 - 获取最大值

Question

与recordKey相关的2个表：

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：结果如下：

TransId ProcessTime
44 4000
55 10

Answer 1

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

Answer 2

也许是这样的？

select transid,transaction.recordkey,max(history.processtime) 
from transaction, history 
where transaction.recordkey=history.recordkey 
group by transid,transaction.recordkey