Subtract dates

[leyburn19]

I want to subtract one date from another to get an integer result

I have a sharepoint list that I want to use update item  to update a number column based two other date columns.  At the moment I have tried placing an expression in teh field to be updated like sub(int('Dateto'),int('DateFrom')) but this fails.

Is there a way to do this?

[v-yuazh-msft]

Hi @leyburn19,

You couldn't use the sub() expression to calculate the number of days difference between two dates.

Does the Dateto and DateFrom are in the same year?

If the Dateto and DateFrom are in the same year, you could use expression below to achieve your needs:

sub(dayOfYear(Dateto),dayOfYear(DateFrom))

You could refer to link below to learn more about the workflow definition language:

https://docs.microsoft.com/en-us/azure/logic-apps/logic-apps-workflow-definition-language

If the Dateto and DateFrom are not in the same year,I afraid that it is difficult to calculate the number of days difference between two dates in microsoft flow currently.

If you would like a function to calculate the number of days difference between two dates to be supported in microsoft flow, please submit an idea to Flow Ideas Forum:

https://powerusers.microsoft.com/t5/Flow-Ideas/idb-p/FlowIdeas

Best regards,

Alice

[leyburn19]

Yes I think a datediff function is really necessary.  That said I am exploring the Ticks().  I create two integer variables and in each one put the a tick formula

Variable 1   ticks(body('Get_item')?['DateFrom']) 

Variable 2   ticks(body('Get_item')?['DateTo'])

When I subtract one from the other I should get a ticks result that can be be divided by the number of ticks in a day leaving a result that should be correct.

I am currently stuck on the latter.  I thought a third variable but fails,  so I tried a compose but this has failed as well

[leyburn19 · Accepted solution]

OK I solved this with the following flow:

 

Variable one expression is

ticks(triggerBody()?['DateFrom'])

Variable 2 expression is

ticks(triggerBody()?['DateTo'])

Variable 3 Expression is

div(sub(variables('Test2'),variables('Test')),864000000000)

So variable 3 gives me the result in teh number of days so that I can update the Days field in SharePoint List

The email is simply a way for me to monitor the process

[JSullivan]

I think it's easier to use DATEDIF as a calculated third column in the list itself.