如何明智地对列进行总和

Question

我在表中有以下数据：

qty      dttime
15.83   2015-04-28 18:58:25.000
3.78    2015-04-28 18:58:27.000
29.39   2015-04-28 18:59:41.000
25.6    2015-04-29 19:01:23.000
2.39    2015-04-29 19:04:24.000
8.9     2015-04-30 19:07:25.000
8.18    2015-04-30 19:10:32.000
1.92    2015-04-30 19:13:48.000

现在我想明智地计算 qty 日期的总和并显示如下输出：

qty      dttime

49      2015-04-28 
27.99   2015-04-29 
19      2015-04-30

我怎样才能对所有这些数据求和并按日期排序？

Answer 1

您可以使用 date 数据类型提取日期（自 SQL Server 2008 起）。剩下的只是聚合：

select cast(dttime as date) as dte, sum(qty)
from t
group by cast(dttime as date)
order by dte;

Answer 2

使用cast():

select sum(qty) qty,  cast(dttime as date) dttime 
from table t
group by cast(dttime as date);