Subtract number of days based on provided date parameter

问题

I created a pipeline in data factory and I want to retrieve data from a source for the current month and for the previous month. When I run the pipeline I give the needed parameter named ExtractDate. The format is MM/DD/YYYY . For the current month I used the following expression in 'Set Variable' activity:

@replace(item().Query,'EXTRACTDATE',formatDateTime(variables('ExtractDate'), 'yyyyMM'))

And for the previous month I tried:

@adddays(variables('ExtractDate'),-28)

The problem appears when the user will set when running the pipeline the date 07/31/2019 for example. Then the previous month will still be July. And if I increase the number to 31, then there is a possibility that the user will introduce 03/01/2019 and from March it will skip the month of February.

I tried to think of a solution, but unfortunately there is no 'addmonths' available in data factory.

Any ideas please?...I've spent 2 days on this issue..

回答1:

addMonths and addYears are not supported by ADF so far.Please vote up this thread to push the progress.

My trick is use combination of bulit-in functions in ADF. Please see my test:

This month is very simple:

@concat(substring('07/16/2019',6,4),substring('07/16/2019',0,2))

output:

Last month is little complex.It should check if it is the first month of the year.

@if(equals(substring('07/16/2019',0,2),'01'), 
concat(
string(sub(
int(substring('07/16/2019',6,4)),1)),
'12'),
string(sub(
int(concat(substring('07/16/2019',6,4),
substring('07/16/2019',0,2))),1)
)
)

if the input param is 01/16/2019,then the output looks like:

My test is based on the static value,please replace it with your variable.

Just for summarize:

The final working dynamic content should be like as below:

@if( equals(variables('SubstringMonth'),'01'), 
concat(string(sub(int(variables('SubstringYear')),1)),'12'), 
concat(variables('SubstringYear'),string(if(or(equals(sub(int(variables('SubstringMonth')),1),11),equals(sub(int(variables('SubstringMonth')),1),10)), 
sub(int(variables('SubstringMonth')),1) , 
concat('0',string(sub(int(variables('SubstringMonth')),1) )))) ))

回答2:

For the previous month from today you could use

    formatDateTime(AddToTime(utcnow(), -1, 'Month'), 'yyyy-MM-dd')

来源：https://stackoverflow.com/questions/57043010/subtract-number-of-days-based-on-provided-date-parameter

标签

azure

azure-data-factory