sql - datediff 没有返回我所期待的

Question

有人知道为什么以下返回 8 吗？我预计 8 小时 30 分钟，还是 8.5？

declare @start_day datetime;
declare @end_day datetime;
declare @start_time datetime;
declare @end_time datetime;

set @start_day = '2014-06-18';
set @end_day = '2014-06-18';
set @start_time = '09:00';
set @end_time = '17:30';

print datediff(hour,@start_day + @start_time, @end_day + @end_time);

Answer 1

试试这个，将分钟的 DATEDIFF 转换为 float ，然后除以 60 得到小时数。

declare @start_day datetime;
declare @end_day datetime;
declare @start_time datetime;
declare @end_time datetime;

set dateformat ymd

set @start_day = '2014-06-18';
set @end_day = '2014-06-18';
set @start_time = '09:00';
set @end_time = '17:30';

print cast(datediff(minute,@start_day + @start_time, @end_day + @end_time) as float) / 60;