Question

我有这样的疑问：

<Window.Resources>
    <Storyboard x:Key="animLOAD" RepeatBehavior="Forever">...</Storyboard>
    <Storyboard x:Key="animPREPARED" RepeatBehavior="Forever">...</Storyboard>
    <Style x:Key="animStyle" TargetType="{x:Type Image}">
        <Style.Triggers>
            <DataTrigger Binding="{Binding Path=st, Mode=OneWay}" Value="LOAD">
                <DataTrigger.EnterActions>
                    <BeginStoryboard Storyboard="{StaticResource animLOAD}" />
                </DataTrigger.EnterActions>
            </DataTrigger>
            <DataTrigger Binding="{Binding Path=st, Mode=OneWay}" Value="PREPARED">
                <DataTrigger.EnterActions>
                    <BeginStoryboard Storyboard="{StaticResource animPREPARED}" />
                </DataTrigger.EnterActions>
            </DataTrigger>
        </Style.Triggers>
    </Style>
</Window.Resources>

<Image Style="{StaticResource animStyle}" />

我从查询中得到了这样的结果：

SELECT Stamp_date , Stamp_Action FROM FILES_TIME_STAMPS
WHERE Stamp_File_Id = @FileID AND Stamp_Action IN (5,15)

减去两条记录的最佳方法是什么？如果我想轻松地与它们一起维护，我怎么能将它们定义为变量呢？

Answer 1

如果您只想减去这两个日期，可以使用DATEDIFF和MIN - MAX

SELECT DATEDIFF(MINUTE, MIN(Stamp_date) , MAX(Stamp_date)) FROM FILES_TIME_STAMPS
WHERE Stamp_File_Id = @FileID AND Stamp_Action IN (5,15)

您可以根据需要将MINUTE更改为SECOND或其他datepart

另外，如果你想根据Stamp_Action选择MIN和MAX，你可以使用它。

SELECT DATEDIFF(MINUTE, 
    MIN(CASE WHEN Stamp_Action = 5 THEN Stamp_date END)  , 
    MAX(CASE WHEN Stamp_Action = 15 THEN Stamp_date END ) ) 
FROM FILES_TIME_STAMPS
WHERE Stamp_File_Id = @FileID AND Stamp_Action IN (5,15)

Answer 2

这是应用LAG函数的好例子：

declare @x table([date] datetime, [value] int)
insert into @x values ('2017-12-04 12:56:37.293', 5), ('2017-12-04 15:40:02.593', 15)

select *,LAG([date], 1) over (order by [date]) [DateLag],
       LAG([value], 1) over (order by [date]) [ValueLag],
       DATEDIFF(minute, [date],LAG([value], 1) over (order by [date])) [DateDifference],
       [value] - LAG([value], 1) over (order by [date]) [ValueDifference]
from @x

我尽可能多地包含了一些例子，所以你可以决定你需要什么，看看它是如何工作的：）

t-sql如何从表中减去两条记录

2 个答案: