问题
How can I select the maximum row from a table? What does maximum mean -- well my table has two timestamp columns, TIME1 and TIME2. The maximum column is the one with the latest value for TIME1. If that is not a unique row, then the maximum is the one within those rows with the latest value for TIME2.
This is on Oracle if that matters.
回答1:
What you need is a "Top-N" query:
select * from ( select * from table order by time1 desc, time2 desc ) where rownum < 2;
if you properly index on time1, time2 it will be very fast:
http://blog.fatalmind.com/2010/07/30/analytic-top-n-queries/
来源：https://stackoverflow.com/questions/3573996/how-can-i-select-the-maximum-row-from-a-table