how to expand a table in DAX

[Jeanxyz]

I have created a table in DAX as below: 

'test = summarize(filter('Fact_GL Entries','Fact_GL Entries'[Item start]>0), 'Fact_GL Entries'[Company Currency],'Fact_GL Entries'[Company Currency Amount],'Fact_GL Entries'[Item start],'Fact_GL Entries'[Item End])

The output will look like this. 

Company Currency	Company Currency Amount	Item start	Item End
EUR	319282	1/1/2023	12/31/2023
…	…	…	…

I want to expland each line of data into multiple lines based on the Item Start month and Item End month, so the first line of data should become 12 lines because the item start in 2023 Jan and ends in 2023 Dec. I would also like to restore the year month information in a new field called [Date Key] . How can I do this in DAX?

Company Currency	Company Currency Amount	Item start	Item End	Date Key
EUR	319282	1/1/2023	12/31/2023	1/1/2023
EUR	319282	1/1/2023	12/31/2023	2/1/2023
EUR	319282	1/1/2023	12/31/2023	3/1/2023
EUR	319282	1/1/2023	12/31/2023	4/1/2023
EUR	319282	1/1/2023	12/31/2023	5/1/2023
EUR	319282	1/1/2023	12/31/2023	6/1/2023
EUR	319282	1/1/2023	12/31/2023	7/1/2023
EUR	319282	1/1/2023	12/31/2023	8/1/2023
EUR	319282	1/1/2023	12/31/2023	9/1/2023
EUR	319282	1/1/2023	12/31/2023	10/1/2023
EUR	319282	1/1/2023	12/31/2023	11/1/2023
EUR	319282	1/1/2023	12/31/2023	12/1/2023

[Dangar332 · Accepted solution]

hi, @Jeanxyz 

make a new table of date with start of every month

like below

then use below code 

just adjust colum name and table name

result table = 
GENERATE(
    'Table',
    FILTER(
        'firstdate',
        MONTH('firstdate'[date])>=MONTH('Table'[Item start])
         && MONTH('firstdate'[date])<=MONTH('Table'[Item End])
    )
)

output like below

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