通过使用两个不同的行获取datediff [英] Get datediff from using two different rows

问题描述

我有一个数据集，其中包含产品的开/关时间.
即

ON = 1
OFF = 0

I have a dataset that contains on/off times for a product.
i.e.

ON = 1
OFF = 0

DeviceID  Event    EventDateTime
1         1        12/07/2012 19:00
1         O        12/07/2012 19:10
1         1        12/07/2012 19:15
1         O        12/07/2012 19:45
1         1        12/07/2012 21:00
1         O        12/07/2012 21:15

因此，我想向数据集中添加一个计算字段(DeviceOnTime)，以显示ON/OFF周期之间的时间差.因此DeviceOnTime应该看起来像这样，即

Thus i want to add a calculated field (DeviceOnTime) to the dataset to show the difference in time between the ON/OFF periods. Thus DeviceOnTime should look like this i.e

DeviceID  Event    EventDateTime       DeviceOnTime
1         1        12/07/2012 19:00
1         O        12/07/2012 19:10    00:10:00
1         1        12/07/2012 19:15
1         O        12/07/2012 19:45    00:30:00
1         1        12/07/2012 21:00
1         O        12/07/2012 21:15    00:15:00

我的问题是执行此操作所需的表达式，这是香港专业教育学院尝试过的，但由于不喜欢以前的功能而刚得到一个错误

我的表情
= IIF(Fields！EventID.Value = 0，DateDiff("h"，Fields！EventDateTime.Value，Previous(Fields！EventDateTime.Value))，什么都没有

这样对吗 ?我可以为计算字段执行此操作吗?

My problem is the expression needed to do this, this what ive tried and a just get an error because it dont like the previous function

My Expression
=IIF(Fields!EventID.Value = 0, DateDiff("h",Fields!EventDateTime.Value, Previous(Fields!EventDateTime.Value)), Nothing)

Is this correct ? can i do this for a calculated field ?

推荐答案

表达式应该可以.我猜想，第一行评估可能会出错(如上一节所述，它什么也不会给出).

试试:

Expression should be ok. I guess, there might be an error for the first row evaluation(as Previous for it will give Nothing).

Try:

=IIF(RowNumber("GroupbyCategory") Mod 2, Nothing, IIF(Fields!EventID.Value = 0, DateDiff("h",Fields!EventDateTime.Value, Previous(Fields!EventDateTime.Value)), Nothing))

它将处理第一行的情况，并为您提供样本中替代行的数据.

It will handle both first row scenario as well give you data for alternate rows as it looks like from your sample.

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