Question

我找不到通过加入同一个表并在新行上显示结果来获取同一个id的timestamp列的最小值和最大值的方法

例如

No | Name    | Date
1    John    01/01/2010
4    Chris   01/02/2009
1    John    01/01/2011
6    Alex    02/02/2010
1    Alex    01/01/2012
4    Norman  01/03/2012
6    Joshua  03/02/2012

I should somehow get :
No |   Name    | Date
1      John     01/01/2010
1      Alex     01/01/2012
4      Chris    01/02/2009
4      Norman    01/03/2012
6       Alex     01/01/2012
6      Joshua    03/02/2012

Answer 1

简单的MIN和MAX会完成这项工作还是会有更复杂的要求？

SELECT no, name, MIN(date) as MinDate, MAX(date) as MaxDate
FROM temp t
GROUP BY no, name
ORDER BY no

演示：http://sqlfiddle.com/#!3/8243c/3

编辑：可以这样做：

select t.no, name, mindate, maxdate
from temp t
left join (select min(date) as mindate, no
           from temp 
           group by no) t2 on t.no = t2.no
left join (select max(date) as maxdate, no
           from temp 
           group by no) t3 on t.no = t3.no

Answer 2

这将为您提供所需的确切输出：

select no, name, date
  from temp t
 where date = (select min(x.date) from temp x where x.no = t.no)
    or date = (select max(x.date) from temp x where x.no = t.no)
 order by no, date

SQL小提琴演示：http://sqlfiddle.com/#!3/8243c/6/0

编辑 - 如果您想使用JOIN：

select t.no, t.name, t.date
  from temp t
  join (select no, min(date) as min_date, max(date) as max_date
          from temp
         group by no) x
    on (t.no = x.no and t.date = min_date)
    or (t.no = x.no and t.date = max_date)
 order by t.no, t.date

http://sqlfiddle.com/#!3/8243c/19/0

（相同的输出）

加入同一个表，并在不同的行上按id获取时间戳的最大值和最小值

2 个答案: