在SQL Server中执行日期/时间减法

Question

我在一个表中有四个字段：

date entered, time entered, date completed, time completed

我想知道输入日期/时间和完成日期/时间的区别

例如

date entered = 1/1/2001
time entered = 10:00
time completed = 1/2/2001
time completed = 11:00

差别是25个小时。

如何使用select语句执行此计算？

我刚试过这个：

DATEDIFF(hh,dateadd(hh,[Time Entered],[Date Entered]),dateadd(hh,[Time Completed],[Date Completed]) ) AS [Hours]

并得到以下错误：

Msg 8116, Level 16, State 1, Line 2
Argument data type time is invalid for argument 2 of dateadd function.

Answer 1

Declare @dateentered date = '20010101'
Declare @timeentered time = '10:00' 
Declare @datecompleted date = '20010102' 
Declare @timecompleted time = '11:00'

select datediff(hh, @dateentered + cast(@timeentered as datetime), 
                    @datecompleted + cast(@timecompleted as datetime))

因此，就表的列而言：

select datediff(hh, [date entered] + cast([time entered] as datetime), 
                    [date completed] + cast([time completed] as datetime)) as [Hours]

Answer 2

select datediff(hour,'1/1/2001 10:00','1/2/2001 11:00')

Answer 3

使用DateDiff