如何在postgres中获得具有最大时间戳的行？

Question

我需要在postgresql中获取一行最大时间戳的信息.以下是此问题的演示:

drop table Mytable cascade
create table MyTable (usr char(1), event_dt timestamp without time zone);
insert into mytable values ('A','01-JAN-2009 11:10:11');
insert into mytable values ('A','02-JAN-2009 11:10:22');
insert into mytable values ('B','02-JAN-2009 01:01:59' );
insert into mytable values ('C', '31-DEC-2008 02:02:02');
insert into mytable values ('D', '31-DEC-2008 03:03:03');

如果我做

select max(event_dt) from (
select usr,event_dt from mytable where usr= 'A') as foo 

这是我需要的,但它只返回event_dt"2009-01-02 11:10:22"

我想要usr以及来自该行的event_dt.我该怎么做？

Answer 1

我只想去......

SELECT usr, event_dt FROM mytable ORDER BY event_dt DESC LIMIT 1