Question

价格日期时间 1.0 20100815 1 1.2 20100815 2 1.3 20100815 3 2 20100814 1 3.1 20100813 1 3.2 20100813 2 ：：：

现在我想一直选择最新的3天价格，我这样使用

select price, date from allquotes where date in 
      (select date from allquotes group by date order by date desc limit 3)

这是对的吗？这有效吗？有什么建议可以改善这个吗？

如果我想在最新时间只显示一个价格，该怎么做？

非常感谢！

Answer 1

这应该可以解决SQL Server上的问题：

select top 3 q.pricee, q.date, q.time
from (
    select date, max(time) as MaxTime
    from allquotes
    group by date
) qm
inner join quotes q on qm.date = q.date and qm.MaxTime = time
order by date desc

对于MySQL，请尝试：

select q.pricee, q.date, q.time
from (
    select date, max(time) as MaxTime
    from allquotes
    group by date
) qm
inner join quotes q on qm.date = q.date and qm.MaxTime = time
order by date desc
limit 3

Answer 2

Select Top 3 Sum(price),
             date,
             Sum(time)
From   allquotes
Group By date
Order By date Desc

从表中选择最新的ONE日数据

2 个答案: